Mixed-Organic-Cation (FA)x(MA)1–xPbI3 Planar Perovskite Solar Cells with 16.48% Efficiency via a Low-Pressure Vapor-Assisted Solution Process

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• 作者：Jing Chen ; Jia Xu ; Li Xiao ; Bing Zhang ; Songyuan Dai ; Jianxi Yao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 25, 2017
• 年：2017
• 卷：9
• 期：3
• 页码：2449-2458
• 全文大小：677K
• ISSN：1944-8252

文摘

Compared to that of methylammonium lead iodide perovskite (MAPbI<sub>3sub>), formamidinium lead iodide perovskite (FAPbI<sub>3sub>) has a smaller energy band gap and greater potential efficiency. To prevent the transformation of α-FAPbI<sub>3sub> to δ-FAPbI<sub>3sub>, preparation of (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> was regarded as an effective route. Usually, the planar (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> perovskite solar cells are fabricated by a solution process. Herein, we report a low-pressure vapor-assisted solution process (LP-VASP) for the growth of (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> perovskite solar cells that features improved electron transportation, uniform morphology, high power conversion efficiency (PCE), and better crystal stability. In LP-VASP, the (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> films were formed by the reaction between the PbI<sub>2sub> film with FAI and MAI vapor in a very simple vacuum oven. LP-VASP is an inexpensive way to batch-process solar cells, avoiding the repeated deposition solution process for PbI<sub>2sub> films, and the device had a low cost. We demonstrate that, with an increase in the MAI content, the (101) peak position of FAPbI<sub>3sub> shifts toward the (110) peak position of MAPbI<sub>3sub>, the (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> perovskites are stable, and no decomposition or phase transition is observed after 14 days. The photovoltaic performance was effectively improved by the introduction of MA<sup>+sup> with the highest efficiency being 16.48% under conditions of 40 wt % MAI. The carrier lifetime of (FA)<sub>xsub>(MA)<sub>1–xsub>PbI<sub>3sub> perovskite films is approximately three times longer than that of pure FAPbI<sub>3sub>. Using this process, solar cells with a large area of 1.00 cm<sup>2sup> were fabricated with the PCE of 8.0%.