Regulating crystallization dynamics and crystal orientation of methylammonium tin iodide enables high-efficiency lead-free perovskite solar cells

Long Ji; Ting Zhang; Yafei Wang; Detao Liu; Hao Chen; Hualin Zheng; Xuefeng Peng; Shihao Yuan; Zhi David Chen; Shibin Li

doi:10.1039/d1nr06802d

Regulating crystallization dynamics and crystal orientation of methylammonium tin iodide enables high-efficiency lead-free perovskite solar cells

Nanoscale. 2022 Jan 27;14(4):1219-1225. doi: 10.1039/d1nr06802d.

Authors

Long Ji^{1

2}, Ting Zhang¹, Yafei Wang¹, Detao Liu¹, Hao Chen¹, Hualin Zheng¹, Xuefeng Peng¹, Shihao Yuan¹, Zhi David Chen³, Shibin Li^{1

4}

Affiliations

¹ School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, China. shibinli@uestc.edu.cn.
² Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
³ Department of Electrical & Computer Engineering and Center for Nanoscale Science & Engineering, University of Kentucky, Lexington, Kentucky 40506, USA.
⁴ Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, P. R. China.

PMID: 34989751
DOI: 10.1039/d1nr06802d

Abstract

Tin (Sn)-based perovskite solar cells (PSCs) have attracted much attention because they are more environmentally friendly than lead-based PSCs. However, the fast crystallization of Sn-based perovskite films and the easy oxidation of Sn²⁺ to Sn⁴⁺ hinder the improvement of their efficiency and stability. In this work, ethylammonium bromide (EABr) was added to methylammonium tin iodide (MASnI₃) perovskite precursor solution to regulate the crystallization dynamics and improve the film morphology. The results show that the large EA⁺ ions slow down the crystallization process of Sn-based perovskites and form a smooth perovskite film with high crystallinity, while the added Br^- anions further improved the crystallinity and orientation of the perovskite film. Under the combined action of EA⁺ and Br^- ions, the as-produced PSCs achieved a champion power conversion efficiency (PCE) of 9.59%. The EABr additive also retarded the oxidation of Sn²⁺, and the solar cell device maintained 93% of its initial efficiency after 30 days in a nitrogen-filled glove box without being encapsulated. This work provides a new strategy for the realization of high-efficiency Sn-based PSCs.