Improved efficiency of PbS quantum dot sensitized NiO photocathodes with naphthalene diimide electron acceptor bound to the surface of the nanocrystals Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2018-01-11 Mahfoudh Raissi, Muhammad T. Sajjad, Yoann Farré, Thomas J. Roland, Arvydas Ruseckas, Ifor D.W. Samuel, Fabrice Odobel
Modelling of flexible thin-film modules for building and product integrated photovoltaics Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2018-01-06 N. Bednar, A. Caviasca, P. Sevela, N. Severino, N. Adamovic
In this work we present a simulation of performance of curved thin-film modules for building and product integrated photovoltaic applications. Flexibility of design and possibility of achieving irregular shapes is important feature in these markets. The photovoltaic module model presented in this work is based on a coupled two-step model. The first 1D model describes the technology and outputs device current density in dependence of voltage, temperature, illumination, etc. The second 3D model uses this data as one of its inputs, and describes size, shape and interconnection of the individual cells within the curved flexible module. In this way power production of such photovoltaic system can be assessed in reasonable time and computing resources. Two study cases are presented: a dome shaped solar street lamp and a conic shaped active rooftop shading for a skylight.
Controllable and large-scale fabrication of rectangular CuS network films for indium tin oxide-and Pt-free flexible dye-sensitized solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2018-01-05 Zijie Xu, Teng Li, Qian Liu, Fayin Zhang, Xiaodan Hong, Shuyao Xie, Changxu Lin, Xiangyang Liu, Wenxi Guo
Fabrication and characteristics of composite phase change material based on Ba(OH)2·8H2O for thermal energy storage Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2018-01-03 Qiangqiang Xiao, Wenhui Yuan, Li Li, Tao Xu
Light-trapping enhanced thin-film III-V quantum dot solar cells fabricated by epitaxial lift-off Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2018-01-03 F. Cappelluti, D. Kim, M. van Eerden, A.P. Cédola, T. Aho, G. Bissels, F. Elsehrawy, J. Wu, H. Liu, P. Mulder, G. Bauhuis, J. Schermer, T. Niemi, M. Guina
We report thin-film InAs/GaAs quantum dot (QD) solar cells with n−i−p+n−i−p+ deep junction structure and planar back reflector fabricated by epitaxial lift-off (ELO) of full 3-in wafers. External quantum efficiency measurements demonstrate twofold enhancement of the QD photocurrent in the ELO QD cell compared to the wafer-based QD cell. In the GaAs wavelength range, the ELO QD cell perfectly preserves the current collection efficiency of the baseline single-junction ELO cell. We demonstrate by full-wave optical simulations that integrating a micro-patterned diffraction grating in the ELO cell rearside provides more than tenfold enhancement of the near-infrared light harvesting by QDs. Experimental results are thoroughly discussed with the help of physics-based simulations to single out the impact of QD dynamics and defects on the cell photovoltaic behavior. It is demonstrated that non radiative recombination in the QD stack is the bottleneck for the open circuit voltage (VocVoc) of the reported devices. More important, our theoretical calculations demonstrate that the VocVoc offset of 0.3 V from the QD ground state identified by Tanabe et al., 2012, from a collection of experimental data of high quality III-V QD solar cells is a reliable – albeit conservative – metric to gauge the attainable VocVoc and to quantify the scope for improvement by reducing non radiative recombination. Provided that material quality issues are solved, we demonstrate – by transport and rigorous electromagnetic simulations – that light-trapping enhanced thin-film cells with twenty InAs/GaAs QD layers reach efficiency higher than 28% under unconcentrated light, ambient temperature. If photon recycling can be fully exploited, 30% efficiency is deemed to be feasible.
InAs thermophotovoltaic cells with high quantum efficiency for waste heat recovery applications below 1000 °C Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-29 Qi Lu, Xinxin Zhou, Andrey Krysa, Andrew Marshall, Peter Carrington, Chee-Hing Tan, Anthony Krier
InAs thermophotovoltaic (TPV) cells with external quantum efficiency at the peak wavelengths reaching 71% at low temperature and 55% at room temperature are reported, which are the highest values to date for InAs. The TPV exhibited 10% power conversion efficiency at 100 K cell temperature. The dark and light current-voltage characteristics were measured at different cell temperatures (100–340 K) in response to heat sources in the range 500–800 °C. The resulting dependences of the output voltage and current as well as the spectral response of the InAs TPV have been extensively characterized for waste heat recovery applications. The performance of these cells is strongly determined by the dark current which increases rapidly with increasing cell temperature originating from bandgap narrowing, which resulted in a reduction of open circuit voltage and output power.
Silica fume/capric acid-palmitic acid composite phase change material doped with CNTs for thermal energy storage Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-29 Ahmet Sarı, Alper Bicer, Amir Al-Ahmed, Fahad A. Al-Sulaiman, Md. Hasan Zahir, Shamseldin A. Mohamed
Surface and bulk effects of K in Cu1−xKxIn1−yGaySe2 solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-29 Christopher P. Muzzillo, Timothy J. Anderson
Broadband spectral response of diamond wire sawn mc-Si solar cell with omnidirectional performance and improved appearance Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-29 Y.F. Zhuang, S.H. Zhong, H.Y. Xu, W.Z. Shen
Highly efficient diamond wire sawn (DWS) multi-crystalline Si (mc-Si) solar cells with a satisfactory visual appearance are expecting to dominate the photovoltaic industry soon. Here, we report the realization of broadband spectral response of DWS mc-Si solar cells with omnidirectional performance and improved appearance. The success lies in the effective surface texturization based on MACE technique followed by post acid modification and the introduction of SiO2/SiNx stack layers on the rear side. Bowl-like pits with an open size of about 1 µm are uniformly formed on the Si surface regardless of the crystallographic directions, which significantly enhances the antireflection ability in the short wavelength and makes the grain boundaries less noticeable. We have also shown that the bowl-like textured cells possess exceptional optical absorption over wide angles of incidence from 0° to 70°. Moreover, the SiO2/SiNx stack layers enhance the rear internal reflection and passivation, effectively increasing the long wavelength absorption and suppressing the electrical losses. We have successfully mass-produced DWS mc-Si solar cells with an average efficiency of 19.1%, which is 1.2% absolutely higher than that of the conventional micro-textured counterparts.
Investigating coating method induced vertical phase distribution in polymer-fullerene organic solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-27 C.Y. Jiang, V. Chellappan, W.P. Goh, J. Zhang
The morphologies of bulk heterojunction (BHJ) films of blended semiconductor of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) deposited by doctor blading and spin coating were investigated. Controlled phase separation in BHJ organic/polymer solar cells (OSCs) were achieved using doctor blading. The results revealed that the coating method induced a significant difference in the film morphology. The vertical phase distribution of the BHJ layer fabricated by doctor blading was uniform, while uneven phase distribution was observed in spin coated BHJ layer. The uniform phase distribution in the doctor blading coated film resulted in higher charge carrier mobility and power conversion efficiency in solar cell than those in films fabricated from spin coating. The results demonstrated that doctor blading has advantages not only in large area high throughput and roll-to-roll compatibility, but also in better control of film morphology to achieve high efficiency consistently in OSC devices.
Ultra-broadband perfect solar absorber by an ultra-thin refractory titanium nitride meta-surface Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-27 Zhengqi Liu, Guiqiang Liu, Zhenping Huang, Xiaoshan Liu, Guolan Fu
Electromagnetic wave absorbers with thinner structural thickness but with broader spectral absorption bandwidth are more desirable for various applications in solar energy and optoelectronics. In this work, a refractory titanium nitride meta-surface with efficient, ultra-broadband solar energy absorption is theoretically designed and numerically demonstrated. The resulting 250-nm-thick meta-surface absorber exhibits an ultra-broadband perfect absorption over the whole ultraviolet-visible-near infrared range. With taking the A > 90% into account, the absorption bandwidth is up to 1110 nm with the wavelength range varied from 0.316 μm to 1.426 μm. The titanium nitride nano-resonators array and its coating structure of titanium dioxide array cooperatively provide multiple resonant modes, which therefore introduce strong coupling with the solar radiation and eventually produce an ultra-broadband absorption. The absorption spectrum can be feasibly manipulated via tuning the structural parameters. Most importantly, in sharp contrast to the common absorbers formed with metallic nano-resonators, the titanium nitride based solar absorber is with much stronger thermal stability, illustrating the impressive promise for wide applications such as thermo-photovoltaics and other high-power optoelectronic processes.
Thickness dependent surface roughness of sputtered Li2.5TaOx ion conductor and its effect on electro-optical performance of inorganic monolithic electrochromic device Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-26 Yu Xiao, Guobo Dong, Junji Guo, Qirong Liu, Qingjiao Huang, Qianqian Zhang, Xiaolan Zhong, Xungang Diao
Transparent amorphous Li2.5TaOx thin films with different thicknesses were deposited by RF magnetron sputtering. The ionic conductivities of as-deposited films determined by ac impedance spectroscopy were of the order of 10−8 S/cm at room temperature. The surface roughness increased rapidly with the film thickness increasing as confirmed by scanning electron microscopy and atomic force microscopy. Inorganic monolithic electrochromic devices (ECDs) based on WO3//NiO complementary structure were fabricated using the Li2.5TaOx with different thicknesses as the ion conductor layers. The electro-optical performance of the ECDs was characterized by cyclic voltammetry and chronoamperometry. The ECDs showed a highest optical modulation of 40% at 550 nm driven by − 1.5 V (coloration) and 1 V (bleaching) with switching time of 30 s. Both the amount of transferred charge and coloration efficiency were found to be highly dependent on the film thickness of Li2.5TaOx layer. The high charge transfer resistance at the Li2.5TaOx/WO3 interface and poor growth of WO3 layer due to the high surface roughness of Li2.5TaOx may well account for the decreased device performance.
Properties of glycerol and ethylene glycol mixture based SiO2-CuO/C hybrid nanofluid for enhanced solar energy transport Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-26 Suleiman Akilu, Aklilu Tesfamichael Baheta, Mior Azman M.Said, Alina Adriana Minea, K.V. Sharma
Measurement of dust sweeping force for cleaning solar panels Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-24 Eugene Yu-Ta Chen, Lian Ma, Yuan Yue, Bing Guo, Hong Liang
A new methodology has been developed to evaluate cleaning efficiency of dust particles on solar panels. Those particles have an average diameter of 2.3 µm and were collected in Doha, Qatar. A brush-disk configuration was constructed to measure the sweeping force as a polymeric tip sliding through a dusted glass substrate. The sweeping force was measured under various applied loads on samples treated in environment of various humidity. Experimental results showed that the cleaning efficiency of dry dust particles was independent of the applied load, reaching higher than 90%. However, the adsorption of water molecules showed pronounced effects on the cleaning efficiency. In order to increase the efficiency in humid environment, the applied load thus needed to be increased. The higher the applied load, the higher the sweeping force, the higher the cleaning efficiency, indicating more power is needed to clean the surface. This research presented an alternative approach to evaluate the cleaning efficiency of dust particles.
Tuning orientation of doped hematite photoanodes for enhanced photoelectrochemical water oxidation Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-24 Song Li, Jiajia Cai, Yinglei Liu, Meiqi Gao, Feng Cao, Gaowu Qin
Increase in conversion efficiency of above 14% in Cu(In,Ga)3Se5 (β-CIGS) solar cells by Na2S incorporation through the surface of β –CIGS film Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-24 Ji Hye Kim, Seung Tae Kim, Liudmila Larina, Byung Tae Ahn, KiHwan, Jae Ho Yun
Partially shaded III-V concentrator solar cell performance Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-23 L.A.A. Bunthof, S. Veelenturf, E.J. Haverkamp, W.H.M. Corbeek, D. van der Woude, G.J. Bauhuis, P. Mulder, E. Vlieg, J.J. Schermer
Currently, an important concern in CPV is inhomogeneity of the light distribution on the cell introduced by the applied optical systems, which may affect system performance. In BICPV applications, the inhomogeneities can be much more severe because of design constraints introduced by the building incorporation. Additionally, one of the predominant loss mechanisms in CPV solar cells is perimeter recombination. In this study, the electrical parameters of CPV cells are investigated under inhomogeneous illumination intensity profiles. Partial shading is used as a model for extremely inhomogeneous illumination, while several shadow patterns are used to study the effect of perimeter recombination on the cell performance. As the latter occurs most strongly in GaAs subcells, shallow and deep junction GaAs CPV cells have been developed and subjected to these experiments, as well as commercial triple junction CPV cells. Deep junction GaAs cells are shown to perform significantly better under concentrated light than their shallow junction counterparts. A large degree of shading exceeding 70% has been found to cause only minor losses in the cell performance of 4%. Also, the cell performance is found to be independent of the location of illumination, in spite of perimeter recombination effects, because the current density spreads out. Clearly, increased illumination inhomogeneities caused by elaborate BICPV optical systems, do not inhibit the electrical performance strongly. As a consequence, a large degree of design freedom exists for the optical systems, which offers good opportunities to develop BICPV that meet all the design challenges of the built environment.
CdTe thin film solar cells with a SnTe buffer layer in back contact Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-23 Zeping Weng, Songsong Ma, He Zhu, Zhenyu Ye, Tianyu Shu, Jie Zhou, Xuanzhi Wu, Huizhen Wu
Multicrystalline silicon assisted by polycrystalline silicon slabs as seeds Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-23 Chunlai Huang, Huali Zhang, Shuai Yuan, Yihua Wu, Xinhao Zhang, Da You, Lei Wang, Xuegong Yu, Yuepeng Wan, Deren Yang
An effective method of using polycrystalline silicon (poly-Si) planar slabs as seed materials for industrial low-cost and high-quality seed-assisted multicrystalline silicon has been presented. The interspace volume of the poly-Si slab seed layer is much lower compared to poly-Si nugget seed layer, so the initial grains of the slab-assisted ingot are much more uniform than those of the nugget-assisted ingot. Photoluminescence (PL) and minority lifetime measurements showed a considerable reduction in dislocation cluster density in the slab-assisted ingot, especially at the middle and top regions. The average cell efficiency based on the slab-assisted ingot is enhanced by 0.12% in absolute value compared to the nugget-assisted ingot. Moreover, the bottom edge of slab-assisted ingot can be fully recycled through existing cleaning process without remaining SiC particles, which saves considerable materials and slicing costs in mass manufacturing compared to nugget-assisted growth method.
Synthesis and optoelectrochemical properties of a magenta-to-transmissive electrochromic polymer based on 3, 4-dioxythiophene Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-23 Xiaoming Chen, Qishu Qu
A new magenta-to-transmissive electrochromic polymer, poly(3,4-bis(3-bromopropoxy)thiophene) (PBBrPOT) was synthesized by electrochemical polymerization and its electrochromic properties were characterized in detail. Compared with the representative “large-volume alkyl substituents” strategy, herein we use bromines as the end-capping groups of two propoxyl substituents on the 3- and 4- position of the thiophene ring to introduce more steric repulsion within the polymer chains, and therefore obtain a magenta neutral state of the polymer. The PBBrPOT film shows a set of reasonable electrochromic features, including low driving potentials (−0.1 V and 0.9 V), appropriate transmittance change (38% at 556 nm), but a relatively longer response time in bleaching process (t95 = 6.5 s).
CuNbO3 as a solar energy converter to fuel and electricity Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-22 César Tablero Crespo
Accessing externally induced spatially-resolved strain in GaAs thin-film solar cells by electroluminescence imaging Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-22 Xiaobo Hu, Liangqing Zhu, Guoen Weng, Shaoqiang Chen
Light-induced current mapping in oxide based solar cells with nanoscale resolution Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-21 Shrabani Panigrahi, Tomás Calmeiro, Rodrigo Martins, Elvira Fortunato
Solid state ITO|Au-NPs|TiO2 plasmonic based solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-21 Adam Ginsburg, Maayan Priel, Hannah Noa Barad, David A. Keller, Elana Borvick, Kevin Rietwyk, Adi Kama, Simcha Meir, Assaf Y. Anderson, Arie Zaban
Plasmonic enhanced solar cells are widely studied due to their increased performance arising from the metallic nanoparticles light absorption and scattering. In contrast, there are only few reports on solar cells which are based solely on the plasmonic metallic layer as the absorber. These cells are operating by hot electron injection in a Schottky barrier formed between the metallic nanoparticles and a semiconductor. In this work, we present photovoltaic cells which are based on an ultra-thin tunable Au layer as the only light absorbing material. These cells are in the solid state configuration composed of ITO|Au NP's|TiO2. High throughput methods are used in order to optimize the performance, which reaches 1 mA cm−2 of current, and a voltage of 100 mV under one sun illumination. The incident photon to electron conversion efficiency is 5.84% at 700 nm, the highest reported for a solid-state device so far. These cells are the first step towards a plasmonic based tandem cell.
Effective impurity gettering by phosphorus- and boron-diffused polysilicon passivating contacts for silicon solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-21 AnYao Liu, Di Yan, Sieu Pheng Phang, Andres Cuevas, Daniel Macdonald
This paper presents direct experimental evidence for the strong impurity gettering effects associated with the formation of both phosphorus and boron doped polysilicon/oxide passivating contacts for silicon solar cells, doped via thermal diffusion from POCl3 or BBr3 sources. Ion-implanted iron is used as a marker to quantify the gettering effectiveness via carrier lifetime measurements. The process conditions for fabricating optimum polysilicon passivating contacts are found to remove more than 99.9% of the iron from the silicon wafer bulk. The gettering effects of POCl3 and BBr3 diffused polysilicon/oxide contacts mainly arise from the dopant diffusions, as opposed to gettering by structural defects in the polysilicon films. The thin oxide interlayer hinders the gettering effectiveness at low diffusion temperatures, although its blocking effect becomes small at the moderate temperatures used to fabricate optimum polysilicon contacts. The gettering effectiveness increases with increasing diffusion temperature. The gettering of iron from the silicon wafer bulk to the surface layers is found to have a negligible impact on their ability to suppress recombination at the interface with the silicon wafer. Therefore, the formation of polysilicon/oxide passivating contacts, via thermal diffusion from POCl3 and BBr3 sources, not only achieves high quality surface and contact passivation but also has the net additional benefit of achieving very effective gettering of unwanted impurities in the silicon wafer bulk.
Low-temperature solution-processed ionic liquid modified SnO2 as an excellent electron transport layer for inverted organic solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-19 Van-Huong Tran, Rizwan Khan, In-Hwan Lee, Soo-Hyoung Lee
Automated design of multi junction solar cells by genetic approach: Reaching the >50% > 50 % efficiency target Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-13 Slobodan Čičić, Stanko Tomić
The proper design of the multi-junction solar cell (MJSC) requires the optimisation search through the vast parameter space, with parameters for the proper operation quite often being constrained, like the current matching throughout the cell. Due to high complexity number of MJSC device parameters might be huge, which makes it a demanding task for the most of the optimising strategies based on gradient algorithm. One way to overcome those difficulties is to employ the global optimisation algorithms based on the stochastic search. We present the procedure for the design of MJSC based on the heuristic method, the genetic algorithm , taking into account physical parameters of the solar cell as well as various relevant radiative and non-radiative losses. In the presented model, the number of optimising parameters is 5 M + 1 for a series constrained M -junctions solar cell. Diffusion dark current, radiative and Auger recombinations are taken into account with actual ASTM G173-03 Global tilted solar spectra, while the absorption properties of individual SCs were calculated using the multi band k·p k · p Hamiltonian. We predicted the efficiencies in case of M=4 M = 4 to be 50.8% 50.8 % and 55.2% 55.2 % when all losses are taken into account and with only radiative recombination, respectively.
Challenges and strategies for implementing the vertical epitaxial heterostructure architechture (VEHSA) design for concentrated photovoltaic applications Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-12 Mark C.A. York, Antoine Mailhot, Abderraouf Boucherif, Richard Arès, Vincent Aimez, Simon Fafard
Monochromatic conversion efficiencies in excess of 60% have been achieved with Vertical Epitaxial HeteroStructure Architechture laser power converters (with anywhere from 5 to 20+ n/p junctions stacked vertically). We are presently investigating the applicability of this design to solar cells, whereby the individual junctions of a multi-junction cell are replaced with a current matched stack of subcells. If viable, such a design offers the potential for efficiency gains via reduced I2R I 2 R losses and elevated Voc V oc . Moreover, splitting the short-circuit current over additional junctions opens up the possibility of operation under concentration ratios otherwise considered impractical for conventional cells.
Work function optimization of vacuum free top-electrode by PEDOT:PSS/PEI interaction for efficient semi-transparent perovskite solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-11 Kang Min Kim, Sunyong Ahn, Woongsik Jang, Soyun Park, O Ok Park, Dong Hwan Wang
Electrochromism of hexagonal sodium tungsten bronze nanorods Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-12-08 Tao Gao, Bjørn Petter Jelle
Single-crystalline sodium tungsten bronze (Na-WO3) nanorods with typical diameters of 10–200 nm and lengths of several microns have been prepared via a simple hydrothermal method. The as-prepared Na-WO3 nanorods crystallize in a hexagonal structure and elongate along the <001> crystallographic direction. The as-prepared Na-WO3 nanorods have eight diagnostic Fourier transform infrared (FTIR) absorptions at 3604, 3545, 1622, 1600, 983, 790, 480 and 430 cm−1, which represent specific fingerprints of the vibrational features of hexagonally tunnel-structured Na-WO3 containing tunnel water molecules. The as-prepared Na-WO3 nanorods exhibit a typical cathodic electrochromism, which is related to a proton-electron double insertion process. X-ray diffraction results indicate a phase transformation of hexagonal Na-WO3 nanorods during the electrochromic process, of which the involved local structural evolutions such as water decomposition and proton insertion have been discussed by using FTIR spectroscopy. The results suggest that, during the electrochromic coloration process, the inserted protons might occupy the small trigonal tunnel positions instead of the large hexagonal ones.
Relative impacts of methylammonium lead triiodide perovskite solar cells based on life cycle assessment Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-22 Jaume-Adrià Alberola-Borràs, Rosario Vidal, Emilio J. Juárez-Pérez, Elena Mas-Marzá, Antonio Guerrero, Iván Mora-Seró
The environmental performance of four different device assembly procedures based on hybrid halide perovskite solar cell (PSC) were assessed from cradle to grave using life cycle assessment (LCA) methodology. In addition, a new environmental indicator was defined to measure the time evolution of an impact category, specifically in this case, human toxicity cancer payback time. PSCs procedures accounted for the probably three more used basic recipes for laboratory perovskite deposition: 1) spin coating of stoichiometric precursor solution, 2) spin coating of precursor solution using lead chloride precursor and 3) the two step deposition method. Also, the two most widely used substrate configurations (planar and mesoporous substrate)were considered. LCA included three realistic scenarios for the end of life: 1) residual landfill, 2) reuse and residual landfill and 3) reuse and recycling. The remaining variable parameters to assemble the device were fixed in common for all four devices, which were the major responsible of the whole PSC impact. Lead of PSCs had no significant contribution in environmental impacts. Beyond shared procedure steps, impacts generated by the two-step method and the use of mesostructured type substrate were higher. End of life scenario with reuse and recycling improved the toxicity impact categories.
On the use of metal cation-exchanged zeolites in sorption thermochemical storage: Some practical aspects in reference to the mechanism of water vapor adsorption Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-22 Delhia Alby, Fabrice Salles, Julien Fullenwarth, Jerzy Zajac
The sodium form of industrial X-zeolite (13X) was compared with two other samples obtained by a partial (about 70%) cation exchange with Mg2+ (Mg-X) or a complete exchange with Ca2+ (Ca-X) in view of their use as adsorbents for water vapor in energy storage systems by sorption. Various sorption methods based on the specific interactions between two probing molecules (N2 and NH3) and specific surface sites were employed to monitor the hydration state of the zeolite surface as a function of the temperature of sample drying performed under vacuum degassing or gas-flow conditions. X-ray diffraction, volumetric sorption technique, temperature-programmed desorption, and gas flow calorimetry were combined with Monte Carlo simulations of the mechanism of water vapor adsorption on model zeolites to demonstrate that the general tendency to operate under mild drying conditions would always result in a state of partial hydration of the zeolite surface. To increase the amount of heat released upon subsequent adsorption from a flow of helium at a relative pressure of water vapor of about 0.03, the use of Mg-X sample was demonstrated the best alternative if the activation procedure was to be performed at 200 °C. Here, the heat effect was 4–5 times greater than that measured in the case of 13X. This result is of high importance for the industrial-scale implementation of the energy storage by sorption.
Sebacic acid/CNT sponge phase change material with excellent thermal conductivity and photo-thermal performance Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-22 Qi Zhang, Jian Liu
Latent heat thermal energy storage system using phase change materials was widely used in solar thermal systems. Here, a novel form-stable phase change composite was successfully prepared. The sebacic acid is encapsulated by carbon nanotube sponge. The as-prepared composite is determined by SEM, FT-IR and XRD and the results show that the paraffin is mostly encapsulated in the pores of carbon nanotube sponge. The DSC measurements indicate that the melting temperature and latent heat of the composite are 121.1 °C and 131.8 J g−1, respectively. The phase change composite could maintain its phase transition perfectly after 200 melting−freezing cycles, and no leakage of sebacic acid was observed by further SEM observation. The as-prepared composite shows 27-fold thermal conductivity enhancement as compared to the pure sebacic acid. Further, the as-prepared composite shows great photo-thermal performance when under simulated solar irradiation. Hence, the carbon nanotube sponge based high temperature phase change composite has great potential in solar thermal application.
A practical wave-optical hemispheroidal nanostructure strategy for photonic-enhanced thin film solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-21 Qian Huang, Xiaoyuan Lin, Yupeng Tong, Jian Ni, Li Zhang, Xiaonan Lu, Ying Zhao, Xiaodan Zhang
The interaction between light and wavelength-sized photonic nanostructure is highly promising for light management applied to thin-film photovoltaics (PVs). In this work, we put forward a practical wave-optical dielectric hemispheroidal nanostructure strategy under cost-effective anodic oxidation approach and substrate transfer method. By adjusting the oxidation voltage, periodic hemispheroidal nanostructure with diametral scale over 650 nm was obtained. Due to their wavelength-scale dimension, enhanced diffraction behavior and guided resonance were identified through finite-difference-time-domain (FDTD) simulation resulting in significant forward-scattering capabilities. The coherent optical performance was investigated experimentally and theoretically. To leverage the benefits of hemispheroidal nanostructure, amorphous silicon absorb layer and solar cell were fabricated. Compared with the planer structure, the developed hemispheroidal nanostructure could significantly improve the absorption of a-Si:H layer via light management with a 10.97% enhancement in the overall external quantum efficiency. Effective improvements in Voc and FF performances were also obtained in comparison to an etched AZO structure with high surface roughness. As the first demonstration, it was found that the hemispheroidal nanostructure by coating on the surface of a-Si:H thin film solar cells led to 7.79% and 7.38% enhancements respectively in overall energy conversion efficiency in comparison to the planar and the etched AZO structure.
Corrosion of steel alloys in molten NaCl + Na2SO4 at 700 °C for thermal energy storage Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-21 Madjid Sarvghad, Geoffrey Will, Theodore A. Steinberg
Stainless steel 316, duplex steel 2205 and carbon steel 1008 were examined for compatibility with the eutectic mixture of NaCl + Na2SO4 at 700 °C in air for thermal energy storage. Electrochemical measurements combined with advanced microscopy techniques were employed. Results confirmed oxidation to be the primary attack to all metals. Ferritic alloy 1008 was found the most vulnerable alloy with severe oxidative attack. Alloys 316 and 2205 showed close performance while grain boundary oxidative and sulfur attack threatened these materials. Alloy 2205 showed chromium depletion followed by selective oxidation of ferrite in the presence of a semi-protective film on the surface.
Boron subphthalocyanines as electron donors in outdoor lifetime monitored organic photovoltaic cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-20 Richard K. Garner, David S. Josey, Stephanie R. Nyikos, Aleksa Dovijarski, Jon M. Wang, Greg J. Evans, Timothy P. Bender
Structural variants of boron subphthalocyanines were tested as light absorbing and electron donating materials paired with C60 in organic photovoltaic cells, in a rooftop ambient environment according to ISOS-O3 protocols. Constant current monitoring and daily current-voltage sweeps, reinforced by irradiance and temperature tracking, reveal differing degradation rates depending on the chemical structure of the boron subphthalocyanine. Results suggest that the observed initial burn-in efficiency loss observed in all devices is due to C60, but that the longer term degradation trend is attributable to the chemical breakdown of the subphthalocyanine donors through hydrolysis. These findings demonstrate that the molecular structure of boron subphthalocyanines is a significant handle on device longevity, and that a structure-property relationship can be established for stability. The results also highlight the need for alternative electron accepting materials to C60 for pairing with boron subphthalocyanines in planar heterojunction solar cells, as well as the necessity of a more robust encapsulation methodology.
Eutectic composition-dependence of latent heat of binary carbonates (Na2CO3/Li2CO3) Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-20 Zhiwei Ge, Yun Huang, Yulong Ding
Phase change materials (PCMs) are promising alternative candidates for a variety of thermal energy storage and related applications. Among the PCMs, alkali carbonates have received particular attention in recent years due to their favourable thermophysical properties at high temperatures. However, the use of such carbonates as PCM requires the understanding of the structural information of the material particularly at both the solid and molten states and the composition dependence of the latent heat, which are largely lacking. Here we study, by both experiments and molecular dynamics simulations, the latent heat of the binary carbonates Na2CO3/Li2CO3. The results show that the binary carbonates can convert to LiNaCO3 within a wide concentration range. A eutectic composition (EC) region of about 51 mol. % Li2CO3 has shown the largest conversion to the LiNaCO3. Any excess loading of Na2CO3 or Li2CO3 beyond the EC region of the carbonates could lower the activation energy of diffusion. The solidification of the carbonates leads to a higher phase change resistance in the EC region with a higher activation energy Ea(pc) and a larger latent heat during the phase change.
ZnO-Au composite hierarchical particles dispersed oil-based nanofluids for direct absorption solar collectors Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-20 Xinzhi Wang, Yurong He, Meijie Chen, Yanwei Hu
Direct absorption solar collector (DASC) is a promising technology for solar energy harvesting. Recently, nanofluids have shown great potential for DASC applications due to their tunable optical absorption properties. An advanced composite combining plasmonic gold nanoparticles (Au NPs) and hedgehog-like hierarchically structured ZnO particles (HPs) was prepared and used in DASCs. The nanofluid prepared with 1.0 mg mL−1 HP-Au exhibited excellent stability and broadband optical absorption properties, and reached an equilibrium temperature of ~125 °C within 1 h of solar heating at an irradiation power of 10 kW m−2. A new photothermal conversion efficiency model was established to evaluate the solar harvesting performance of the HP-Au/oil nanofluid by simultaneously considering the effect of the working fluid temperature on the heating and cooling efficiencies. Compared to the base fluid, the HP-Au/oil nanofluid exhibits a 240% enhancement in photothermal conversion efficiency. The HP-Au/oil nanofluid shows great potential as a working fluid in direct absorption solar collectors.
Influence of MgCl2 content on corrosion behavior of GH1140 in molten NaCl-MgCl2 as thermal storage medium Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-20 Jun-wei Wang, Hong-xia Zhou, Cui-zhen Zhang, Wen-ning Liu, Bai-yao Zhao
As a thermal energy storage medium (TESM) at moderate-high temperature of concentrating solar power (CSP), the molten NaCl-MgCl2 has sharp corrosive action on a metal container. The influence of MgCl2 content on a metal corrosion behavior is not clear. The corrosion behavior of a Fe based alloy (GH1140) in molten NaCl-MgCl2 (at 1123 K) with different content of MgCl2 (wt%：0.0，48.9，61.0，93.6) were studied by the submergence corrosion experience. Results show that: after corrosion for 5 h, there is a negative correlation between the weight loss of samples and the content of MgCl2. In the molten salt without MgCl2, the sample was corroded according to the mechanism of “dissolution as anode- oxidizing- peeling off of oxide film”. After adding a little MgCl2 in the molten salt, an unprotected MgO shell was formed on the sample surface. The samples weight decreased and obeyed a line law. The elements of Fe and Cr deplete in the corrosion layer. Corrosion mechanism is “dissolution as anode- oxidizing- reduction- chlorination”. When the content of MgCl2 is very high in the molten salt, partial pressure of Cl2 increases. The corrosion mechanism is similar to what in the molten salt with a little MgCl2, but the chlorination reaction is more severe.
Degradation of multijunction photovoltaic gridlines induced via thermal cycling Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-20 Ryan E. Brock, Peter Hebert, James Ermer, Reinhold H. Dauskardt
A well-known but heretofore uncharacterized failure mechanism in multijunction photovoltaic cells involves the development of cracks in the top cell directly adjacent to metal gridline structures. In this study, we systematically explore the potential evolution of stress, grain size, roughness, and hardness of metal gridlines during thermal cycling as it pertains to top cell cracking behavior. We discover that although top cells are found to crack after many cycles, this is not due to an accumulation of stress or damage, but rather a progression of strain hardening within the metal gridlines due to cyclic plastic deformations, quantified as an increase in hardness of as much as 57%. Furthermore, optical and topological characterization reveals morphology changes at the gridlines’ top surfaces, lending some insight to commonly observed bus bar wire-bonding issues. Ultimately this suite of characterization techniques not only reveals the underlying behavior leading to gridline-induced top cell cracking failures in multijunction photovoltaics, but also suggests a route forward for the development of improved gridline materials.
Characterization of medium-temperature phase change materials for solar thermal energy storage using temperature history method Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-16 Zhaowen Huang, Ning Xie, Zigeng Luo, Xuenong Gao, Xiaoming Fang, Yutang Fang, Zhengguo Zhang
In this work, thermal properties of five phase change materials (PCMs) with medium phase change temperature including mannitol, sebacic acid (SA), SA/expanded graphite (EG) composite, LiNO3-KCl eutectic salt and LiNO3-KCl/EG composite, were characterized using temperature history (T-history) method with improved accuracy. The studies on mannitol showed that although the T-history method could yield a supercooling degree which was lower than that from differential scanning calorimetry (DSC) determination, the severe supercooling and great latent heat loss during mannitol's solidification were still the problems which hindered the use of this material. As for the rest materials, slight or no supercooling phenomena were observed and the obtained phase change temperatures were well matched to literature data. The latent heat measurements of these four materials proved a proportional relationship between the PCM/EG composite's latent heat and PCM's mass fraction. However, the latent heat values determined by T-history were higher than the DSC results. Therefore, repeated studies were still required to further evaluate the latent heat storage densities of these materials. The results in this work could play key roles in design, simulation and modification of latent thermal energy storage (LTES) systems based on these medium-temperature PCMs for solar heat applications.
Up-scalable sheet-to-sheet production of high efficiency perovskite module and solar cells on 6-in. substrate using slot die coating Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-16 Francesco Di Giacomo, Santhosh Shanmugam, Henri Fledderus, Bardo J. Bruijnaers, Wiljan J.H. Verhees, Maarten S. Dorenkamper, Sjoerd C. Veenstra, Weiming Qiu, Robert Gehlhaar, Tamara Merckx, Tom Aernouts, Ronn Andriessen, Yulia Galagan
Scalable sheet-to-sheet slot die coating processes have been demonstrated for perovskite solar cells and modules. The processes have been developed on 6 in. × 6 in. glass/ITO substrates for two functional layers: the perovskite photo-active layer and the Spiro-OMeTAD hole transport layer. Perovskite solar cells produced using these slot die coating processes demonstrate device performances identical to the spin coated devices. All manufactured devices illustrate a high level of reproducibility. The developed slot die coating processes were also used for the manufacturing of perovskite PV modules. Large area modules of 12.5 × 13.5 cm2 were realized by slot die coating on 6 in. × 6 in. substrates in combination with newly developed laser ablation processes for conventional P1-P2-P3 monolithic cell interconnections. The modules demonstrate power conversion efficiencies above 10%, with a power output of 1.7 W. This achievement is an important milestone in the development of up-scalable manufacturing technologies for perovskite PV modules.
Printable liquid silicon for local doping of solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-16 Felix Haase, Bianca Lim, Agnes Merkle, Thorsten Dullweber, Rolf Brendel, Christian Günther, Michael H. Holthausen, Christoph Mader, Odo Wunnicke, Robby Peibst
We demonstrate the application of a liquid-processed doped silicon precursor as a doping source for the fabrication of interdigitated back contact solar cells. We integrate phosphorus- as well as boron-doped liquid silicon in our n-type interdigitated back contact cell process based on laser-structuring. The cell with the phosphorus back surface field from liquid silicon has an efficiency of 20.9% and the cell with the boron emitter from liquid silicon has an efficiency of 21.9%. We measure saturation current densities of 34 fA cm−2 on phosphorus-doped layers with a sheet resistance of 108 Ω/sq and 18 fA cm−2 on boron-doped layers with a sheet resistance of 140 Ω/sq using passivated test samples.
On the origin of band-tails in kesterite Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-14 G. Rey, G. Larramona, S. Bourdais, C. Choné, B. Delatouche, A. Jacob, G. Dennler, S. Siebentritt
Kesterite Cu2ZnSn( S x Se 1 − x )4 is an attractive earth-abundant material for low-cost thin film photovoltaics with the capability to achieve power production in the terawatt range and therefore to supply a significant part of the global electricity needs. Despite its advantageous optical and electrical properties for photovoltaic applications, the large band tailing causes voltage losses that limit the efficiency of kesterite-based devices. Here we show that the band-tailing originates mainly from band-gap fluctuations attributable to chemical composition variations at nanoscale; while electrostatic fluctuations play a lesser role. Absorption measurement reveal that the Cu-Zn disorder, always present in kesterite Cu2ZnSn( S x Se 1 − x )4, is not the main source of the large band tailing. Instead defect clusters having a significant impact on the band-edge energies, e.g. [2 Cu Zn − + Sn Zn 2 + ], are proposed as the main origin for the kesterite band tail.
Development of low-cost inorganic salt hydrate as a thermochemical energy storage material Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-14 V. Mamani, A. Gutiérrez, S. Ushak
Thermochemical storage is based on a reversible chemical reaction; energy can be stored when an endothermic chemical reaction occurs and then, energy is released when it is reversed in an exothermic reaction. According to literature and based on the energy storage density (esd), MgCl2·6H2O is a promising candidate material for thermochemical energy storage. Bischofite is an inorganic salt obtained as a by-product material from extraction processes of non-metallic minerals, from Salar de Atacama in Chile, containing approximately 95% of MgCl2·6H2O. Thus, the purpose of this study was to characterize the dehydration reaction of bischofite ore, studied as a low-cost thermochemical storage material. Thermogravimetric data for bischofite were obtained using a TGA instrument coupled to a DSC, at four different isotherms 70 °C, 80 °C, 90 °C and 100 °C. The results of conversion reaction (α-t) from the thermal dehydration experiments, demonstrated the first phase of dehydration with the loss of two water molecules. The study showed a typical sigmoid curve with a significant acceleration in the conversion at the beginning of the reaction until it reaches a maximum rate, where the curve keeps constant. The same behavior was observed for all the temperatures used. The kinetics of bischofite dehydration model was determined using the isothermal kinetics method. For this, the thermogravimetric data were fitted to the most used kinetic models (D, F, R, A) and then their respective correlation coefficients R were evaluated. The results indicated that the dehydration reaction of bischofite was described by the kinetics of chemical reaction of cylindrical particles R2. The rate of dehydration reaction and esd of bischofite are lower as compared to synthetic MgCl2·6H2O, at temperatures higher than 80 °C. However, the cost of materials to store 1 MJ of energy is three times lower for bischofite, which is an evident advantage to promote the reuse of this material left as waste by the non-metallic industry.
New switchable mirror device with a counter electrode based on reversible electrodeposition Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-13 Seong M. Cho, Sujung Kim, Tae-Youb Kim, Chil Seong Ah, Juhee Song, Sang Hoon Cheon, Joo Yeon Kim, Hojun Ryu, Yong-Hae Kim, Chi-Sun Hwang, Jeong-Ik Lee
A new structure for a switchable mirror device based on reversible electrodeposition is proposed. This device does not contain Cu ions in the electrolyte and adapts a counter electrode. The feasibility of the device was evaluated with a WO3 film, which is a well-known electrochromic material, as a counter electrode. Even in the absence of Cu ions, the WO3 film facilitates a clean erase feature in the device. Furthermore, using a pre-deposited Ag film as a working electrode, Ag deposition can be driven at a substantially lower voltage than that in conventional devices. Moreover the deposition current decreases with the progress of Ag deposition, and stops after completion of the deposition process. The results clearly indicate that the tri-bromine ion, which makes the self-erasing circulation, is not generated during Ag deposition process. The new switchable mirror shows excellent bistability and size scale-up is possible because it does not consume continuous current in the mirror state. By appling the proposed technology, a switchable mirror device with a 7 cm × 9 cm active area was successfully fabricated.
Facile synthesis of mesoporous VO2 nanocrystals by a cotton-template method and their enhanced thermochromic properties Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-08 Shaowen Wu, Shouqin Tian, Baoshun Liu, Haizheng Tao, Xiujian Zhao, R.G. Palgrave, G. Sankar, I.P. Parkin
As a very promising thermochromic material, VO2 (M/R) (Monoclinic/Rutile) has not been widely applied in smart windows due to its intrinsic low solar modulation (ΔTsol) and low luminous transmission (Tlum). To address this issue, porous structures have been introduced into the VO2 film. Herein, mesoporous VO2 powders with pore size of about 2–10 nm were synthesized using cotton as template by hydrothermal methods. The pore and crystal size of the synthesized VO2 powders can be reliably controlled by the hydrothermal temperature. The mesoporous VO2 powders were mixed with PVP to prepare the VO2-based nanocomposite films by spin coating. The VO2-based films show a better performance between ΔTsol and Tlum than that appeared in previous reports. Especially, a larger pore size could lead to a higher visible transmittance and a larger crystal size would facilitate the enhancement in the solar modulation. In this sense, the VO2-based film obtained at the hydrothermal temperature of 180 °C exhibits an outstanding thermochromic performance with ΔTsol of 12.9% and Tlum up to 56.0% due to a larger crystal size and pore size. Therefore, this synthetic route shows a potential method for the application of mesoporous VO2 powders for solar control coatings.
Quantitative theoretical and experimental analysis of alloying from screen-printed aluminum pastes on silicon surfaces Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-08 Michael Rauer, Christian Schmiga, Markus Glatthaar, Stefan W. Glunz
In this study, we present detailed theoretical and experimental investigations on full-area alloying from screen-printed aluminum pastes on silicon surfaces for solar cell applications. We introduce a simple analytical model for the description of the alloying process derived from existing models for evaporated Al layers, which we adapt to printed Al pastes. Thereby, we particularly account for the recrystallization of Si within the paste particles, which we refer to as parasitic Si recrystallization. Applying our model, we demonstrate good accordance of calculated with measured eutectic layer thicknesses. We show that the model can be versatilely used to investigate screen-printed Al-alloyed contacts in detail: We demonstrate that the latent heat of the Al paste significantly influences the alloying process. Thus, the effective peak temperature of the alloying process can be several 100 °C below the set peak temperature of the firing furnace. By combining calculations of the effective peak temperature with measurements of the Al doping concentration, we determine a parameterization of the solid solubility of Al in Si down to the eutectic temperature of 577 °C. Our investigations therefore provide improved understanding of alloying from printed Al pastes and enable the specific optimization of Al-alloyed contacts.
One-pot hydrothermal synthesis of thioglycolic acid-capped CdSe quantum dots-sensitized mesoscopic TiO2 photoanodes for sensitized solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-07 Xiaohui Song, Xingna Liu, Yong Yan, Jianping Deng, Yongyong Wang, Xiao Dong, Zhenkun Mo, Congxin Xia
In this work, colloidal CdSe QDs capped with a short chain thiol ligand thioglycolic acid (TGA) were prepared using a one-pot synthesis route in aqueous medium. This method integrates colloidal QDs synthesis and assembly of QDs in a single step due to the use of TGA, which serves as a stabilizer to control the formation of QDs and a linker to tether CdSe QDs to TiO2 during the synthesis of QDs, and it could achieve high surface coverage of high-quality QDs on TiO2 electrodes. The hydrothermal temperature is found to play an important role in determining the size of CdSe QDs and photovoltaic properties of the resulting TiO2/CdSe photoanodes. To further improve the fill factor and efficiency of solar cells, PbS/CuS films were prepared with chemical bath deposition method and used instead of the usual Pt as counter electrodes (CEs). PbS/CuS CEs show superior electrocatalytic activity for the reduction of polysulfide than Pt. An optimized TiO2/CdSe based QDSSC in combination with the PbS/CuS CEs achieved a champion PCE of 4.18% under one sun illumination (100 mW cm−2).
Analysing impact of oxygen and water exposure on roll-coated organic solar cell performance using impedance spectroscopy Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-07 B. Arredondo, B. Romero, M.J. Beliatis, G. del Pozo, D. Martín-Martín, J.C. Blakesley, G. Dibb, F.C. Krebs, S.A. Gevorgyan, F.A. Castro
In this work we study the degradation of roll-coated flexible inverted organic solar cells in different atmospheres. We demonstrate that impedance spectroscopy is a powerful tool for elucidating degradation mechanisms; it is used here to distinguish the different degradation mechanisms due to water and oxygen. Identical cells were exposed to different accelerated degradation environments using water only, oxygen only, and both water and oxygen simultaneously, all of them enhanced with UV light. The photocurrent is dramatically reduced in the oxygen-degraded samples. Impedance measurements indicate that this phenomenon is attributed to defects introduced by absorption of oxygen, which results in an increase of the acceptor impurity (NA) at the cathode interface obtained from a Mott-Schottky analysis. Simultaneously, at the anode interface where PEDOT:PSS is not shielded by the substrate, the nature of degradation differs for the water and oxygen degraded samples. While oxygen + UV light decreases the conductivity of the PEDOT:PSS layer, water + UV light changes the PEDOT:PSS work function inducing a depletion region at the anode.
Evaluation of optical properties and protection factors of a PDLC switchable glazing for low energy building integration Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-06 A. Ghosh, T.K. Mallick
Polymer dispersed liquid crystal (PDLC) glazing is a potential electrically actuated switchable adaptive glazing for low energy building application as it become transparent in the presence of alternating current (AC) power supply and become translucent/opaque without power supply. Optical properties and protection factor for a particular type of PDLC glazing was investigated in this work. Using UV–vis–NIR (1050) spectrophotometer spectral transmittance of this glazing was measured for its both states. PDLC on state needs 20 V AC power supply to offer 41% transmission while without any supply this glazing becomes 23% transparent. In the switch off state LC particles offer forward scattering which makes this glazing translucent with high 82.6% haze. Solar factor for PDLC transparent and translucent state was found to be 0.53 and 0.39 respectively. Glazing protection factors were calculated using spectral transmittance data. Switchable transparency and switchable solar factor makes this glazing suitable to match adaptability of building occupants.
Rheology of Solar-Salt based nanofluids for concentrated solar power. Influence of the salt purity, nanoparticle concentration, temperature and rheometer geometry Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-06 Belén Muñoz-Sánchez, Javier Nieto-Maestre, Elisabetta Veca, Raffaele Liberatore, Salvatore Sau, Helena Navarro, Yulong Ding, Nuria Navarrete, J. Enrique Juliá, Ángel G. Fernández, Ana García-Romero
Solar Salt-based nanofluids have attracted significant scientific interest in recent years due to their improved thermal properties, making them strong candidates as thermal energy storage materials and/or heat transfer fluids in CSP plants. There have been reports on increased specific heat due to the addition of nanoparticles, however, there is a lack of comprehensive information on other essential properties affecting the heat transfer, such as the viscosity. This article concerns the rheological behaviour of nanofluids made of Solar Salt (mass percentage at 60% NaNO3 – 40% KNO3) as the base fluid and silica or alumina nanoparticles as additives. The evolution of these nanofluids viscosity as a function of the shear rate (1–1000 s−1) at a temperature range of 250–400 °C was measured and analysed. The impact of the salt purity (refined or industrial grade), the nanoparticle concentration (0.5–1.5 wt%) and the rheometer measuring configuration (coaxial cylinder or parallel plate) are examined. The results showed in general a Newtonian behaviour of the nanofluids with independency of the rheometer configuration. The relationship between the viscosity and the temperature follows an Arrhenius model. The influence of the nanoparticle concentration on the viscosity of the refined grade Solar Salt is analysed according to the Maron-Pierce and Kriegher-Dougherty models for the nanofluids containing alumina and silica nanoparticles respectively, due to their different shape.
The influence of DMSO and ether via fast-dipping treatment for a perovskite solar cell Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-06 Ki-Hwan Hwang, Sang Hun Nam, Dong In Kim, Hyeon Jin Seo, Jin-Hyo Boo
Preparing dense organic-inorganic hybrid perovskite film is hindered by the extremely low solubility of lead(II) iodide (PbI2) at one-step coating process using one-solution (PbI2 + CH3NH3I + DMF). Thus, dimethyl sulfoxide (DMSO) has been widely used to enhance the solubility through the formation of adducts. However, the required mixture of DMSO and DMF cannot be simultaneously evaporated at low temperatures, owing to the different boiling points, which are influenced by the surface morphology. Consequently, this also affects the solar energy conversion efficiency of the perovskite solar cells. In this study, we develop a new approach for controlling the evaporation of DMF and DMSO by dip-coating ether on the top of the prepared thin film composed of PbI2, methylammonium iodide (MAI), DMF, and DMSO. Interestingly, it reveals that ether acted as an agent for simultaneous evaporation at similar temperatures, which then allows it to control surface morphology, and achieve dense perovskite. The fabricated inverted-perovskite PbI2 thin film solar cell shows that the efficiency reached up to 16.3% with high reproducibility. The ether-dipping post-treatment serves as a promising means for enhancing the efficiency of perovskite solar cells.
Crystalline-Si heterojunction with organic thin-layer (HOT) solar cell module using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS) Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-06 Koji Kasahara, Jaker Hossain, Daisuke Harada, Koki Ichikawa, Ryo Ishikawa, Hajime Shirai
We represent the photovoltaic performance of n-type crystalline silicon (n-Si) heterojunction with organic thin-layer (HOT) solar cell module using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS) together with 4,4′-cyclohexylidenebis [N,N-bis(4-methylphenyl) benzenamine] (TAPC) as a protecting layer of PEDOT:PSS for air storage and barium hydroxide, Ba(OH)2 as a hole blocking layer at the rear c-Si/cathode interface, respectively. PEDOT:PSS/n-Si front-junction solar cell showed a power conversion efficiency (PCE) of 13–14% (11–12%) with a short-circuit density, JSC of 29–31 mA/cm2 (25–26 mA/cm2), an open-circuit voltage, VOC of 0.62 V (0.625 V), and a fill factor, FF of 0.72 (0.704) for a 2 × 2 cm2 (4 in.) size device. Solar cell module consisting of ten-units of series-connected 2 × 2 cm2 (4 in.) sized cells exhibited a output power of 0.37 W (7.3 W) with a VOC of 6.1 V (6.2 V), a JSC of 0.084 A (1.78 A), and a FF of 0.712 (0.71). We also confirmed that it worked as a stand-alone photovoltaic system for remote monitoring of wireless camera drive.
Chinese ink: High performance nanofluids for solar energy Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Han Wang, Weimin Yang, Lisheng Cheng, Changfeng Guan, Hua Yan
Nanofluids have shown competitive performance on solar thermal collection. This work proposes the application of Chinese ink as nanofluid in solar photo-thermal conversion. The dispersion stability of the nanofluid was characterized by spectrophotometer. Compared with reported Cu, CuO nanofluids, that of Chinese ink has shown more satisfied stability of dispersion. The obtained results reveal that the nanofluid of Chinese ink has surprisingly higher efficiency of photo-thermal conversion than that of Cu and CuO nanoparticles. Carbon black is determined for Chinese ink nanofluid to convert solar photo to heat. Bone glue coated on the surface of Chinese ink nanoparticle also plays a significant role that it prevents the carbon black nanoparticles from aggregation and deposition. The preparation process of Chinese ink is pretty simple and the raw materials are cheap and widely available, which promises the large-scale industrial applications of Chinese ink for solar thermal collections.
An efficient and simple tool for assessing singlet oxygen involvement in the photo-oxidation of conjugated materials Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Anthony Perthué, Isabel Fraga Domínguez, Pieter Verstappen, Wouter Maes, Olivier J. Dautel, Guillaume Wantz, Agnès Rivaton
Upon exposure to photooxidative conditions, organic materials are susceptible to undergo degradation via processes involving radical oxygen species and/or reaction with singlet oxygen (1O2). In this frame, the work herein presents a new and straightforward methodology to clarify the role of highly-reactive 1O2 in the photodegradation mechanism of conjugated materials applied in organic electronics. The general methodology consists in the comparison of the infrared signatures of the conjugated materials after the materials are exposed to photooxidative and thermooxidative conditions and in situ generated 1O2. The methodology was validated by analysing the behaviour of four donor materials commonly used in organic solar cells. Analysis of the degradation mechanism of these materials allowed exemplifying the three possible case scenarios, namely (1) both 1O2 and radical oxygen species are involved in the general photooxidation mechanism of the studied material, (2) the material is unreactive towards 1O2 and thus this species plays no role in the photooxidation process, and (3) the conjugated material is reactive towards chemically produced 1O2 but this species is not the main responsible for the photooxidative degradation of the material. In the latter two cases, a free-radical oxidation process accounts for the photooxidation of the investigated materials. The results derived from this simple, yet enlightening, methodology provide fundamental understanding about the degradation pathways of conjugated materials, which is a key point to develop not only efficient but also stable organic electronic devices.
The effect of hole transfer layers and anodes on indium-free TiO2/Ag/TiO2 electrode and ITO electrode based P3HT:PCBM organic solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Zhao Zhao, T.L. Alford
Transparent composite electrodes (TCE), TiO2/Ag/TiO2 (TAgT), have been demonstrated as a promising alternative of indium tin oxide (ITO) in organic solar cell application. TiO2/Ag/TiO2 have been incorporated into bulk heterojunction organic solar cells (OSCs) to replace ITO as the anode. Two different hole transfer layers (HTL), poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and MoO3, are compared in terms of their compatibility with the TiO2/Ag/TiO2 anode. The MoO3 layer has been shown to be a beneficial HTL for TiO2/Ag/TiO2 based OSC. However, the wettability of MoO3 for polymer blend is not as good as PEDOT:PSS, and results in a relatively thin active layer in OSCs. On the other hand, ITO based OSCs using PEDOT:PSS and MoO3 as the HTL are fabricated as control samples to compare the performance of TAgT and ITO anodes. Results of the investigation shows that the superior electrical property of TAgT anodes contributes to the effective collection of photo-carriers and its lower optical transmittance barely degrades the light absorption in OSCs. In a few words, the higher Haacke figure of merit of TAgT enables better performance of OSCs with MoO3 HTL, in comparison with ITO based OSC.
Tailoring Mo(S,Se)2 structure for high efficient Cu2ZnSn(S,Se)4 solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Shoushuai Gao, Yi Zhang, Jianping Ao, Shuping Lin, Zhaojing Zhang, Xiuling Li, Dongxiao Wang, Zhiqiang Zhou, Guozhong Sun, Fangfang Liu, Yun Sun
The direction of Se-Mo-Se sheets to the Mo film is crucial for the thickness of Mo(S,Se)2 and the electrical conductivity, so as the back contact of Cu2ZnSn(S,Se)4 solar cells. In this study, the preferred orientation of Mo(S,Se)2 film changes from (100) peak to (103) peak, i.e. from perpendicular to the substrate to tilted to the substrate for Se-Mo-Se sheets as the roughness decrease of Mo back contact layer. The Se vapor can easily diffuse through the channels between Se-Mo-Se sheets when the formed Mo(S,Se)2 layer is (100) peak preferred with Se-Mo-Se sheets perpendicular to the substrate, and thus excessively thick Mo(S,Se)2 will be formed. Whereas, the Se-Mo-Se sheets are tilted to substrate when the preferred orientation of Mo(S,Se)2 is (103) peak. The tilted Se-Mo-Se sheets can act as a natural Se diffusion barrier to suppress the Se vapor diffusion through the already formed Mo(S,Se)2 layer to further selenize the remaining Mo film, and also can provide a good electrical conductivity. As a result, the thickness of Mo(S,Se)2 sharply decreased from 1500 nm to 200 nm with the surface morphology change of Mo back contact, which resulting in the decrease of series resistance of Cu2ZnSn(S,Se)4 solar cells from 2.94 Ω cm2 to 0.49 Ω cm2, and the increase of conversion efficiency of Cu2ZnSn(S,Se)4 solar cells from 6.98% to 9.04%.
Preparation of phase change material emulsions with good stability and little supercooling by using a mixed polymeric emulsifier for thermal energy storage Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Fangxian Wang, Xiaoming Fang, Zhengguo Zhang
A mixed polymeric emulsifier consisting of polyvinyl alcohol (PVA) and polyethylene glycol-600 (PEG-600) was explored for preparing high-performance phase change material emulsions (PCMEs) containing the paraffin with a melting point of 62–64 °C. After the effects of the mass ratio of PVA to PEG-600, the mass ratio of the mixed emulsifier to the paraffin and the homogenization rate on the size distribution, viscosity and dispersion stability of the PCMEs containing 20 wt% paraffin were systematically investigated, the optimal emulsifying process parameters have been determined to be the mass ratio of PVA to PEG-600 of 50:50, the mass ratio of the mixed emulsifier to paraffin of 1:5 and the homogenization rate of 10,000 rpm. Accordingly, the PCMEs with the paraffin mass fractions varying from 10 wt% to 30 wt% were prepared. It is found that the paraffin has been well dispersed in water in the form of sphere-like droplets with average diameters ranging from 3 µm to 11 µm in the obtained PCMEs. Significantly, the PCMEs with different mass fractions of the paraffin exhibit no supercooling, owing to the function of the mixed polymeric emulsifier as a nucleating agent. The apparent specific heat of PCMEs are 1.51–2.18 times as high as that of water at the phase transition temperature region, due to the existent of the paraffin in them. Their apparent thermal conductivity gradually decreases with an increase in the mass fraction of the paraffin, while the viscosity increases significantly with mass fraction of the paraffin at the same temperatures. Furthermore, the pumping power consumption of the PCMEs shows a drastic reduction as compared to that of water at the same heat storage capacity. It is revealed that the PCMEs show great potential for use as a novel heat transfer fluid (HTF) in thermal energy storage (TES) systems.
Formulation of PC71BM isomers in P3HT-based polymer solar cells Sol. Energy Mater. Sol. Cells (IF 4.784) Pub Date : 2017-11-04 Xin-Xing Zhan, Min-Song Lin, Xu-Zhai Lu, Xing-Yan Tang, Yun-Yan Xu, Tan Wang, Lin-Long Deng, Su-Yuan Xie, Rong-Bin Huang, Lan-Sun Zheng
Formulation engineering, featuring with different ingredients combined, is a useful strategy for making efficient electronic acceptors because it can achieve effects that cannot be obtained from its components when these are used singly. Herein, we show a contour plot with different formulations of isomeric phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptors in poly(3-hexylthiophene) (P3HT):PC71BM polymer solar cells (PSCs). Upon altering fullerene formulation the PCEs change in the range of 0.87–4.01%. The optimized formulation consisting of ~ 80% α-PC71BM, ~ 10% β1-PC71BM, and ~ 10% β2-PC71BM exhibits the best PCE of 4.01%, which mainly benefits from the optimum morphology of P3HT-fullerene heterojunction film. The present work demonstrates a successful strategy by controlling morphology of PC71BM isomers to improve the PCE of P3HT-based PSCs, and consolidates the photovoltaic performance of polymer solar cells heavily dependent on the formulation of fullerene-based electron acceptors.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
- Acc. Chem. Res.
- ACS Appl. Mater. Interfaces
- ACS Biomater. Sci. Eng.
- ACS Catal.
- ACS Cent. Sci.
- ACS Chem. Biol.
- ACS Chem. Neurosci.
- ACS Comb. Sci.
- ACS Earth Space Chem.
- ACS Energy Lett.
- ACS Infect. Dis.
- ACS Macro Lett.
- ACS Med. Chem. Lett.
- ACS Nano
- ACS Omega
- ACS Photonics
- ACS Sens.
- ACS Sustainable Chem. Eng.
- ACS Synth. Biol.
- Acta Biomater.
- Acta Mater.
- Adv. Colloid Interface Sci.
- Adv. Electron. Mater.
- Adv. Energy Mater.
- Adv. Funct. Mater.
- Adv. Healthcare Mater.
- Adv. Mater.
- Adv. Mater. Interfaces
- Adv. Opt. Mater.
- Adv. Sci.
- Adv. Synth. Catal.
- AlChE J.
- Anal. Bioanal. Chem.
- Anal. Chem.
- Anal. Chim. Acta
- Anal. Methods
- Angew. Chem. Int. Ed.
- Annu. Rev. Anal. Chem.
- Annu. Rev. Biochem.
- Annu. Rev. Food Sci. Technol.
- Annu. Rev. Mater. Res.
- Annu. Rev. Phys. Chem.
- Appl. Catal. A Gen.
- Appl. Catal. B Environ.
- Appl. Clay. Sci.
- Appl. Energy
- Aquat. Toxicol.
- Arab. J. Chem.
- Asian J. Org. Chem.
- Atmos. Environ.
- Carbohydr. Polym.
- Catal. Commun.
- Catal. Sci. Technol.
- Catal. Today
- Cell Chem. Bio.
- Cem. Concr. Res.
- Ceram. Int.
- Chem. Asian J.
- Chem. Bio. Drug Des.
- Chem. Biol. Interact.
- Chem. Commun.
- Chem. Educ. Res. Pract.
- Chem. Eng. J.
- Chem. Eng. Sci.
- Chem. Eur. J.
- Chem. Mater.
- Chem. Phys.
- Chem. Phys. Lett.
- Chem. Phys. Lipids
- Chem. Rev.
- Chem. Sci.
- Chem. Soc. Rev.
- Combust. Flame
- Compos. Part A Appl. Sci. Manuf.
- Compos. Sci. Technol.
- Compr. Rev. Food Sci. Food Saf.
- Comput. Chem. Eng.
- Constr. Build. Mater.
- Coordin. Chem. Rev.
- Corros. Sci.
- Crit. Rev. Food Sci. Nutr.
- Crit. Rev. Solid State Mater. Sci.
- Cryst. Growth Des.
- Curr. Opin. Chem. Eng.
- Curr. Opin. Colloid Interface Sci.
- Curr. Opin. Environ. Sustain
- Curr. Opin. Solid State Mater. Sci.
- Ecotox. Environ. Safe.
- Electrochem. Commun.
- Electrochim. Acta
- Energy Environ. Sci.
- Energy Fuels
- Environ. Impact Assess. Rev.
- Environ. Int.
- Environ. Model. Softw.
- Environ. Pollut.
- Environ. Res.
- Environ. Sci. Policy
- Environ. Sci. Technol.
- Environ. Sci. Technol. Lett.
- Environ. Sci.: Nano
- Environ. Sci.: Processes Impacts
- Environ. Sci.: Water Res. Technol.
- Eur. J. Inorg. Chem.
- Eur. J. Med. Chem.
- Eur. J. Org. Chem.
- Eur. Polym. J.
- J. Acad. Nutr. Diet.
- J. Agric. Food Chem.
- J. Alloys Compd.
- J. Am. Ceram. Soc.
- J. Am. Chem. Soc.
- J. Am. Soc. Mass Spectrom.
- J. Anal. Appl. Pyrol.
- J. Anal. At. Spectrom.
- J. Antibiot.
- J. Catal.
- J. Chem. Educ.
- J. Chem. Eng. Data
- J. Chem. Inf. Model.
- J. Chem. Phys.
- J. Chem. Theory Comput.
- J. Chromatogr. A
- J. Chromatogr. B
- J. Clean. Prod.
- J. CO2 UTIL.
- J. Colloid Interface Sci.
- J. Comput. Chem.
- J. Cryst. Growth
- J. Dairy Sci.
- J. Electroanal. Chem.
- J. Electrochem. Soc.
- J. Environ. Manage.
- J. Eur. Ceram. Soc.
- J. Fluorine Chem.
- J. Food Drug Anal.
- J. Food Eng.
- J. Food Sci.
- J. Funct. Foods
- J. Hazard. Mater.
- J. Hydrol.
- J. Ind. Eng. Chem.
- J. Inorg. Biochem.
- J. Magn. Magn. Mater.
- J. Mater. Chem. A
- J. Mater. Chem. B
- J. Mater. Chem. C
- J. Mater. Process. Tech.
- J. Mech. Behav. Biomed. Mater.
- J. Med. Chem.
- J. Membr. Sci.
- J. Mol. Catal. A Chem.
- J. Mol. Liq.
- J. Nat. Gas Sci. Eng.
- J. Nat. Prod.
- J. Nucl. Mater.
- J. Org. Chem.
- J. Photochem. Photobiol. C Photochem. Rev.
- J. Phys. Chem. A
- J. Phys. Chem. B
- J. Phys. Chem. C
- J. Phys. Chem. Lett.
- J. Porphyr. Phthalocyanines
- J. Power Sources
- J. Solid State Chem.
- J. Taiwan Inst. Chem. E.
- Macromol. Rapid Commun.
- Mass Spectrom. Rev.
- Mater. Chem. Front.
- Mater. Des.
- Mater. Horiz.
- Mater. Lett.
- Mater. Sci. Eng. A
- Mater. Sci. Eng. R Rep.
- Mater. Today
- Meat Sci.
- Med. Chem. Commun.
- Microchem. J.
- Microchim. Acta
- Micropor. Mesopor. Mater.
- Mol. Biosyst.
- Mol. Cancer Ther.
- Mol. Catal.
- Mol. Nutr. Food Res.
- Mol. Pharmaceutics
- Mol. Syst. Des. Eng.
- Nano Energy
- Nano Lett.
- Nano Res.
- Nano Today
- Nano-Micro Lett.
- Nanoscale Horiz.
- Nat. Catal.
- Nat. Chem.
- Nat. Chem. Biol.
- Nat. Commun.
- Nat. Energy
- Nat. Mater.
- Nat. Med.
- Nat. Methods
- Nat. Nanotech.
- Nat. Photon.
- Nat. Prod. Rep.
- Nat. Protoc.
- Nat. Rev. Chem.
- Nat. Rev. Drug. Disc.
- Nat. Rev. Mater.
- Neurochem. Int.
- New J. Chem.
- NPG Asia Mater.
- npj 2D Mater. Appl.
- npj Comput. Mater.
- npj Flex. Electron.
- npj Mater. Degrad.
- npj Sci. Food
- Pharmacol. Rev.
- Pharmacol. Therapeut.
- Photochem. Photobiol. Sci.
- Phys. Chem. Chem. Phys.
- Phys. Life Rev.
- PLOS ONE
- Polym. Chem.
- Polym. Degrad. Stabil.
- Polym. J.
- Polym. Rev.
- Powder Technol.
- Proc. Combust. Inst.
- Prog. Cryst. Growth Ch. Mater.
- Prog. Energy Combust. Sci.
- Prog. Mater. Sci.
- Prog. Photovoltaics
- Prog. Polym. Sci.
- Prog. Solid State Chem.