Dong Yueyao, Zhu Wen-Xian, Wu Dong-Tai, Li Xuan, Westbrook Robert J E, Huang Chi-Jing, Min Zeyin, Hong Weiying, Wang Boyuan, Min Ganghong, Sathasivam Sanjayan, Palma Matteo, Dimitrov Stoichko, Lin Chieh-Ting, Macdonald Thomas J
Department of Electronic & Electrical Engineering, University College London, Roberts Building, London WC1E 7JE, U.K.
Department of Chemical Engineering, National Chung Hsing University, Taichung 40227, Taiwan.
J Am Chem Soc. 2025 Sep 3;147(35):31578-31590. doi: 10.1021/jacs.5c05772. Epub 2025 Aug 23.
Mixed tin-lead (Sn-Pb) halide perovskites, with their tunable bandgaps (1.2-1.4 eV), show great promise for the development of highly efficient all-perovskite tandem solar cells. However, achieving commercial viability and stabilized high efficiency for Sn-Pb perovskite solar cells (PSCs) presents numerous challenges. Among various optimization strategies, the incorporation of additives has proven critical in modulating the crystallization of Sn-Pb perovskites. Despite the widespread use of additives to improve performance, detailed photophysical mechanisms remain unclear. In this work, we elucidate the mechanistic role of guanidinium thiocyanate, a chaotropic agent, in the crystallization of Sn-Pb perovskites. We combine hyperspectral imaging with real-time in situ photoluminescence spectroscopy to study the crystallization process of Sn-Pb perovskites. Our findings reveal that the chaotropic agent modulates the crystal growth rate during perovskite crystallization, resulting in more homogeneous films with reduced nonradiative recombination. We challenge the common assumption that crystallization stops once the solvent evaporates by identifying photoluminescence variations during the cooldown process. The resulting films exhibit a photoluminescence quantum yield of 7.28% and a charge carrier lifetime exceeding 11 μs, leading to a device efficiency of 22.34% and a fill factor of over 80%. This work provides a fundamental understanding of additive-mediated crystal growth and transient cooldown dynamics, advancing the design of high-quality Sn-Pb perovskites for efficient and stable optoelectronics.
混合锡铅（Sn-Pb）卤化物钙钛矿具有可调节的带隙（1.2 - 1.4电子伏特），在高效全钙钛矿串联太阳能电池的发展方面显示出巨大潜力。然而，要实现Sn-Pb钙钛矿太阳能电池（PSC）的商业可行性和稳定的高效率面临众多挑战。在各种优化策略中，添加物的引入已被证明对调节Sn-Pb钙钛矿的结晶至关重要。尽管广泛使用添加物来提高性能，但其详细的光物理机制仍不清楚。在这项工作中，我们阐明了硫氰酸胍（一种离液剂）在Sn-Pb钙钛矿结晶过程中的作用机制。我们将高光谱成像与实时原位光致发光光谱相结合，以研究Sn-Pb钙钛矿的结晶过程。我们的研究结果表明，离液剂在钙钛矿结晶过程中调节晶体生长速率，从而形成更均匀的薄膜，减少非辐射复合。我们通过识别冷却过程中的光致发光变化，挑战了溶剂蒸发后结晶就停止的普遍假设。所得薄膜的光致发光量子产率为7.28%，电荷载流子寿命超过11微秒，器件效率达到22.34%，填充因子超过80%。这项工作为添加剂介导的晶体生长和瞬态冷却动力学提供了基本理解，推动了用于高效稳定光电器件的高质量Sn-Pb钙钛矿的设计。
