Wang Pengjiu, Chen Xu, Liu Tianyu, Hou Cheng-Hung, Tian Yue, Xu Xuehui, Chen Zeng, Ran Peng, Jiang Tingming, Kuan Chun-Hsiao, Yan Buyi, Yao Jizhong, Shyue Jing-Jong, Qiu Jianbei, Yang Yang Michael
State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
Small Methods. 2022 May;6(5):e2200048. doi: 10.1002/smtd.202200048. Epub 2022 Mar 9.
The traditional way to stabilize α-phase formamidinium lead triiodide (FAPbI ) perovskite often involves considerable additions of methylammonium (MA) and bromide into the perovskite lattice, leading to an enlarged bandgap and reduced thermal stability. This work shows a seed-assisted growth strategy to induce a bottom-up crystallization of MA-free perovskite, by introducing a small amount of α-CsPbBr /DMSO (5%) as seeds into the pristine FAPbI system. During the initial crystalization period, the typical hexagonal α-FAPbI crystals (containing α-CsPbBr seeds) are directly formed even at ambient temperature, as observed by laser scanning confocal microscopy. It indicates that these seeds can promote the formation and stabilization of α-FAPbI below the thermodynamic phase-transition temperature. After annealing not beyond 100 °C, CsPbBr seeds homogeneously diffused into the entire perovskite layer via an ions exchange process. This work demonstrates an efficiency of 22% with hysteresis-free inverted perovskite solar cells (PSCs), one of the highest performances for MA-free inverted PSCs. Despite absented passivation processes, open-circuit voltage is improved by 100 millivolts compared to the control devices with the same stoichiometry, and long-term operational stability retained 92% under continuous full sun illumination. Going MA-free and low-temperature processes are a new insight for compatibility with tandems or flexible PSCs.
稳定α相甲脒铅三碘化物（FAPbI₃）钙钛矿的传统方法通常需要向钙钛矿晶格中大量添加甲基铵（MA）和溴化物，这会导致带隙增大和热稳定性降低。这项工作展示了一种种子辅助生长策略，通过向原始FAPbI₃体系中引入少量α-CsPbBr₃/DMSO（5%）作为种子，诱导无MA钙钛矿的自下而上结晶。在初始结晶阶段，通过激光扫描共聚焦显微镜观察发现，即使在室温下也能直接形成典型的六方α-FAPbI₃晶体（含有α-CsPbBr₃种子）。这表明这些种子可以在热力学相变温度以下促进α-FAPbI₃的形成和稳定。在不超过100°C的退火后，CsPbBr₃种子通过离子交换过程均匀扩散到整个钙钛矿层中。这项工作展示了无滞后的倒置钙钛矿太阳能电池（PSC）的效率为22%，这是无MA倒置PSC的最高性能之一。尽管没有钝化过程，但与具有相同化学计量比的对照器件相比，开路电压提高了100毫伏，并且在连续全日照下长期运行稳定性保持在92%。无MA和低温工艺是与串联或柔性PSC兼容的新见解。
