Enhanced optoelectronic quality of perovskite films with excess CH3NH3I for high-efficiency solar cells in ambient air. (26th April 2017)

• Record Type: Journal Article
• Authors: Zhang, Yunhai; Lv, Huiru; Cui, Can; Xu, Lingbo; Wang, Peng; Wang, Hao; Yu, Xuegong; Xie, Jiangsheng; Huang, Jiabin; Tang, Zeguo; Yang, Deren
• Is Part Of: Nanotechnology. Volume 28:Number 20(2017)
• Publication Date: 2017-04-26
• Subjects: perovskite solar cells -- CH3NH3PbI3 -- excess methylammonium iodide -- metallic lead -- ambient air -- stability; Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/1361-6528/aa6956
• Languages: English
• ISSNs: 0957-4484

Abstract

Abstract: Solution-processed polycrystalline perovskite films contribute critically to the high photovoltaic performance of perovskite-based solar cells (PSCs). The inevitable electronic trap states at grain boundaries and intrinsic defects such as metallic lead (Pb 0 ) and halide vacancies in perovskite films cause serious carrier recombination loss. Furthermore, the film can easily decompose into PbI2 in a moist atmosphere. Here, we introduce a simple strategy, through a small increase in methylammonium iodide (CH3 NH3 I, MAI), molar proportion (5%), for perovskite fabrication in ambient air with ∼50% relative humidity. Analysis of the morphology and crystallography demonstrates that excess MAI significantly promotes grain growth without decomposition. X-ray photoemission spectroscopy shows that no metallic Pb 0 exists in the perovskite film and the I/Pb ratio is improved. A time-resolved photoluminescence measurement indicates efficient suppression of non-radiative recombination in the perovskite layer. As a result, the device yields improved power conversion efficiency from 14.06% to 18.26% with reduced hysteresis and higher stability under AM1.5G illumination (100 mW cm −2 ). This work strongly provides a feasible and low-cost way to develop highly efficient PSCs in ambient air.