Improving Performance of Lead‐Free Formamidinium Tin Triiodide Perovskite Solar Cells by Tin Source Purification

• Published in: Solar RRL 2018-10, Vol.2 (10), p.n/a
• Main Authors: Gu, Feidan, Ye, Senyun, Zhao, Ziran, Rao, Haixia, Liu, Zhiwei, Bian, Zuqiang, Huang, Chunhui
• Format: Article
• Language: English
• Subjects: lead‐free; perovskite solar cells; purification; reductants; tin‐based perovskites
• ISSN: 2367-198X; 2367-198X
• DOI: 10.1002/solr.201800136

Lead (Pb)‐free tin (Sn)‐based perovskite solar cells (PSCs) have been recognized as one of the solutions to the toxicity of Pb and drawn considerable attention. However, Sn4+ caused by oxidation or incomplete reduction during synthesis severely deteriorates the device performance. Herein, the authors firstly reveal that the addition of Sn powder into the FASnI3 (FANH2CHNH2+) precursor solution prepared from SnI2 with 99% purity leads to great improvement of the device performance with a maximum power conversion efficiency (PCE) of 6.75%, which is, to the best of their knowledge, the highest efficiency among those of the FASnI3‐based PSCs with SnF2 as the only additive, comparable to and even higher than the device fabricated from SnI2 with a high purity of 99.999%. FASnI3‐based solar cells prepared from 99% SnI2 source are fabricated. Sn powder is added into the precursor solutions to reduce Sn4+ and purify SnI2. Recombination centers introduced by Sn4+ are lessened and the photovoltaic parameters of corresponding devices significantly improve, with the power conversion efficiency boosted from 0.09% to a maximum value of 6.75% under AM 1.5G, 100 mW cm−2.