Thermodynamics of cesium lead halide (CsPbX3, x= I, Br, Cl) perovskites
Introduction
Inorganic cesium lead halide (CsPbX3, X = I, Br, Cl) perovskites are an emerging class of materials that find various applications, especially in perovskite solar cells (PSCs). Its generic formula CsPbX3 renders this materials class superior thermal and moisture stabilities compared to hybrid organic-inorganic perovskites (HOIPs, such as CH3NH3PbI3 and HC(CH2)2PbI3), owing to the replacement of intrinsically volatile organic cations (mostly CH3NH3+ and HC(CH2)2+) with their robust inorganic counterpart (Cs+) [[1], [2], [3]]. Such favorable stabilities open avenues for possible large-scale commercialization of inorganic PSCs, in which CsPbX3 materials function as alternatives to traditional light absorbing HOIPs.
Despite tremendous progress in improving the power conversion efficiencies of PSCs, [4] understanding of thermodynamic properties to explain their intrinsic stabilities (or lack thereof) remains scarce. Moreover, previous studies of CsPbX3 based PSCs centered on CsPbI3 and CsPbBr3, whereas CsPbCl3 was claimed to be less of an option for light harvesting, which was largely attributed to its unsuitably large band gap [[5], [6], [7]]. Yet, CsPbCl3 perovskite, especially in the form of quantum dots (QDs), plays a role in optoelectronic applications such as lasing, light-emitting diodes and even photovoltaics. [[8], [9], [10]] It is thus important to understand the thermodynamic properties of CsPbCl3 perovskite, and further, to evaluate the energetics - structure correlations underlying the entire set of CsPbX3 (XI, Br, Cl) perovskites.
Using room temperature solution calorimetry, we measured the thermodynamic properties of CsPbCl3 perovskite. We then evaluated the CsPbX3 stability trend with X moving down the halogen (VIIA) group, correlating their stabilities to structural variations. To complement the CsPbX3 data, we compared the thermodynamic behavior of relevant perovskites, including HOIPs and titanate (oxide) perovskites.
Section snippets
Materials and synthesis
CsPbCl3 was prepared via solution synthesis: a 1:1 precursor solution of equimolar CsCl and PbCl2 was prepared by dissolving 1.2 mmol cesium chloride (CsCl, Alfa Aesar, 99.9 %) and 1.2 mmol lead chloride (PbCl2, Sigma Aldrich, 99.999 %) into 2 ml anhydrous dimethyl sulfoxide (99.9 % DMSO, Sigma Aldrich) at room temperature (25 °C). Magnetic stirring was applied to aid the dissolution of CsCl and PbCl2 until an even precursor solution was obtained. The precursor solution was evenly applied to a
Results and discussion
The X-ray diffraction (XRD) pattern of CsPbCl3 is shown in Fig. 1, which confirms pure CsPbCl3 in its cubic phase. A schematic crystal structure of cubic CsPbCl3 is also depicted.
The measured solution enthalpies in DMSO of CsPbCl3 and constituent halides are given in Table 1. Earlier findings on CsPbI3 and CsPbBr3 [11,12], as well as the thermochemical cycle to calculate the formation enthalpy of CsPbCl3 are also included. A table with individual experiments for each dissolution enthalpy (used
Conclusions
We conclude that thermodynamic stability of these halide perovskites increases as the Goldschmidt tolerance factor increases towards unity, in the order CsPbI3, CsPbBr3 and CsPbCl3, along with a diminution of thermodynamic difference between the high temperature and low temperature polymorphs. Cesium lead iodide (CsPbI3), the inorganic lead halide perovskite with the most suitable bandgap for solar cell applications among CsPbX3 perovskites, is barely stable under ambient conditions, and thus
CRediT authorship contribution statement
Bin Wang: Conceptualization, Methodology, Investigation, Writing - original draft. Alexandra Navrotsky: Conceptualization, Project administration, Writing - review & editing.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgment
This work was supported by the U.S. Department of Energy Office of Basic Energy Science, grant DE-FG02-03ER46053.
References (34)
- et al.
Thermodynamics of formation of hybrid perovskite-type methylammonium lead halides
J. Chem. Thermodyn.
(2018) - et al.
Energetics of compounds (A2+B4+O3) with the perovskite structure
J. Solid State Chem.
(1988) - et al.
Formation enthalpies of LaLn’O3 (Ln' = Ho, Er,Tm and Yb) interlanthanide perovskites
J. Solid State Chem.
(2015) - et al.
Antiferroelectric Transition in CsPbCl3
Phys. Lett. A
(1969) - et al.
High-temperature structural evolution of caesium and rubidium triiodoplumbates
J. Phys. Chem. Solids
(2008) - et al.
Stabilizing perovskite structures by tuning tolerance factor: formation of formamidinium and cesium lead iodide solid-state alloys
Chem. Mater.
(2016) - et al.
Chemical stability and instability of inorganic halide perovskites
Energy Environ. Sci.
(2019) - et al.
All inorganic halide perovskites nanosystem: synthesis, structural features, optical properties and optoelectronic applications
Small
(2017) - et al.
Halide perovskite photovoltaics: background, status, and future prospects
Chem. Rev.
(2019) - Best Research‐Cell Efficiencies,...
The emergence of perovskite solar cells
Nat. Photonics
Bandgap-tunable cesium lead halide perovskites with high thermal stability for efficient solar cells
Adv. Energy Mater.
Cesium lead halide perovskites with improved stability for tandem solar cells
J. Phys. Chem. Lett.
Nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I): novel optoelectronic materials showing bright emission with wide color gamut
Nano Lett.
Broad wavelength tunable robust lasing from single-crystal nanowires of cesium lead halide perovskites (CsPbX3, X = Cl, Br, I)
ACS Nano
Giant photoluminescence enhancement in CsPbCl3 perovskite nanocrystals by simultaneous dual-surface passivation
ACS Energy Lett.
Energetics, structures, and phase transitions of cubic and orthorhombic cesium lead iodide (CsPbI3) polymorphs
J. Am. Chem. Soc.
Cited by (25)
Research progress in hybrid light-emitting diodes based on quantum dots and organic emitters
2024, Journal of LuminescenceInfluence of anion hardness in (001) surface of CsPbX<inf>3</inf> (X = F, Cl, Br and I) halide perovskites
2023, Journal of Solid State ChemistryStability of CsPbX<inf>3</inf> (X=Br, Cl, I) perovskite nanocrystalline
2022, Journal of Solid State ChemistryCitation Excerpt :From the perspective of thermodynamics, the thermodynamic stability of CsPbX3(X = Br, Cl, I) perovskite nanocrystals increases with the tolerance factor approaching 1. The thermodynamic stability of MAPbX3(X = Br, Cl, I) and MTiO3 perovskites increases with the increase of tolerance factors, and the changes of the thermodynamic stability of other oxides perovskites are similar [80]. Juan [81] et al. used molecular dynamics simulation and appropriate force field study to show that the influence of relatively small amount of water on the formation of perovskite is lower than the well-known influence of water on the structural stability of perovskite.