Bottom-Up Quasi-Epitaxial Growth of Hybrid Perovskite from Solution Process-Achieving High-Efficiency Solar Cells via Template​-Guided Crystallization.

Zhang, Hengkai; Qin, Minchao; Chen, Zhiliang; Yu, Wei; Ren, Zhiwei; Liu, Kuan; Huang, Jiaming; Zhang, Yaokang et al. · Adv Mater · 2021

basic_science · Level V

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Abstract

Epitaxial growth gives the highest-quality crystalline semiconductor thin films for optoelectronic devices. Here, a universal solution-processed bottom-up quasi-epitaxial growth of highly oriented α-formamidinium lead triiodide (α-FAPbI<sub>3</sub> ) perovskite film via a two-step method is reported, in which the crystal orientation of α-FAPbI<sub>3</sub> film is precisely controlled through the synergetic effect of methylammonium chloride and the large-organic cation butylammonium bromide. In situ GIWAXS visualizes the BA-related intermediate phase formation at the bottom of film, which serves as a guiding template for the bottom-up quasi-epitaxial growth in the subsequent annealing process. The template-guided epitaxially grown BAFAMA perovskite film exhibits increased crystallinity, preferred crystallographic orientation, and reduced defects. Moreover, the BAFAMA perovskite solar cells demonstrate decent stability, maintaining 95% of their initial power conversion efficiency after 2600 h ambient storage, and 4-time operation condition lifetime enhancement.