Iodine and Chlorine Element Evolution in CH3NH3PbI3–xClx Thin Films for Highly Efficient Planar Heterojunction Perovskite Solar Cells

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• 作者：Chenghao Cao ; Chujun Zhang ; Junliang Yang ; Jia Sun ; Shuping Pang ; Han Wu ; Runsheng Wu ; Yongli Gao ; Chengbin Liu
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：28
• 期：8
• 页码：2742-2749
• 全文大小：557K
• 年卷期：0
• ISSN：1520-5002

文摘

Highly efficient planar heterojunction perovskite solar cells (PHJ–PSCs) with a structure of ITO/PEDOT:PSS/CH₃NH₃PbI_3–xCl_x/PCBM/C₆₀/Ag was fabricated, in which the compact and pinhole-free CH₃NH₃PbI_3–xCl_x perovskite thin film was obtained using a mixture of precursors containing lead iodide (PbI₂), lead chloride (PbCl₂), and methylammonium iodide (CH₃NH₃I) at an optimized ratio of 1:1:4. The morphology and formation process of CH₃NH₃PbI_3–xCl_x thin film was closely related to the annealing temperature and time, which would result in the controllable performance for the PHJ–PSC devices. The morphology, crystallization process, and element analysis suggested that the chlorine gradually diffused and sublimated from the film surface while the iodine moved to the surface, together with the removal of the pinholes in the film. The PHJ–PSCs with the as-prepared CH₃NH₃PbI_3–xCl_x thin film showed good performance and excellent repeatability. The power conversion efficiency (PCE) up to 14.03% was achieved without obvious hysteresis under different scanning conditions. The understanding of the iodine and chlorine element evolving process during the thermal treatment is beneficial to develop a more efficient scalable one-step solution processing method for fabricating large-area, highly efficient CH₃NH₃PbI_3–xCl_x-based PSCs.