A Spiro fluorene-based dopant-free hole-transporting material denoted as Spiro-IA has been designed and developed from inexpensive starting materials with high yield via a simple synthetic approach for application in perovskite solar cells (PSCs). The unit cost of Spiro-IA can be as low as 1/9^th that of the conventional Spiro-OMeTAD. Moreover, Spiro-IA shows good solubility in different organic solvents, e.g. CHCl₃, acetone, EtOH, and DMF, and showed favorable charge-transport ability and greater photocurrent density compared to Spiro-OMeTAD. The UV absorption/emission spectra of Spiro-IA (λ_max = 430 nm, E_max = 601 nm) are red shifted compared to those of Spiro-OMeTAD (λ_max = 388 nm, E_max = 414 nm) with larger stokes shift values (171 nm) which helps suppress the loss of incident photons absorbed by the HTM and is more beneficial for improving the performance of PSCs. Optical and electrochemical studies show that Spiro-IA fulfilled the basic requirements of the hole transfer and electron regeneration process in the fabricated devices. PSCs fabricated (surface area = 1.02 cm²) with dopant-free Spiro-IA achieved a maximum power conversion efficiency (PCE) of 15.66% (J_SC = 22.14 mA cm⁻², V_OC = 1.042 V, FF = 0.679%), which was comparable to that of the most commonly used Li-doped Spiro-OMeTAD (PCE = 15.93%, J_SC = 20.37 mA cm⁻², V_OC = 1.057 V, FF = 0.74%) and surpassed that of the dopant-free Spiro-OMeTAD (PCE = 9.34%). Additionally, the PSCs based on dopant-free Spiro-IA achieved outstanding long-term stability and favorable conductivity (σ = 2.104 × 10⁻⁴ S cm⁻¹) compared to those based on Spiro-OMeTAD (σ = 9.00 × 10⁻⁸ S cm⁻¹). DFT studies were performed using Gaussian 09 at the B3LYP/6-31G (d/p) level to investigate their electron cloud delocalization in HOMO/LUMO levels. These results showed that Spiro-IA could be a promising candidate for low-cost PSC technology and has a great chance to supersede the expensive Spiro-OMeTAD.

中文翻译：

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新型低成本无掺杂空穴传输材料的合成，低成本，该材料可与Spiro-OMeTAD媲美，可实现高效钙钛矿太阳能电池

一种由Spiro-IA制成的基于Spiro芴的无掺杂空穴传输材料，通过一种简单的合成方法，由廉价的原料以高收率设计和开发而成，可应用于钙钛矿太阳能电池（PSC）。的单位成本螺IA可以低至1/9^个与以往的螺环-OMeTAD。此外，Spiro-IA在不同的有机溶剂（例如CHCl ₃，丙酮，EtOH和DMF）中显示出良好的溶解性，并且与Spiro-OMeTAD相比，具有良好的电荷传输能力和更大的光电流密度。Spiro-IA的紫外吸收/发射光谱（λ_最大= 430纳米，ê_最大= 601纳米）红移相比，这些的螺环-OMeTAD（λ_最大= 388纳米，ê_最大= 414纳米）与较大的斯托克斯位移值（171纳米），其有助于抑制损失HTM吸收的入射光子的数量，对于改善PSC的性能更有利。光学和电化学研究表明，Spiro-IA满足了所制造器件中空穴传输和电子再生过程的基本要求。使用不含掺杂剂的Spiro-IA制造的PSC（表面积= 1.02 cm ²）实现了15.66％的最大功率转换效率（PCE）（J _SC = 22.14 mA cm ^-2，V _OC = 1.042 V，FF = 0.679％），与最常用的掺Li的Spiro-OMeTAD相当（PCE = 15.93％，Ĵ _SC =20.37毫安厘米^-2，V _OC = 1.057 V，FF = 0.74％）和超出的自由掺杂剂的是螺环-OMeTAD（PCE = 9.34％）。此外，基于无掺杂剂Spiro-IA的PSC拥有出色的长期稳定性和良好的导电性（σ = 2.104×10 ^-4 S cm ^-1）与基于Spiro-OMeTAD的结果（σ = 9.00×10 ^-8 S cm ^-1）进行比较。使用高斯09在B3LYP / 6-31G（d / p）水平上进行DFT研究，以研究它们在HOMO / LUMO水平上的电子云离域。这些结果表明，Spiro-IA可以成为低成本PSC技术的有希望的候选者，并且有很大的机会取代昂贵的Spiro-OMeTAD。