Suppression of Charge Carrier Recombination in Lead-Free Tin Halide Perovskite via Lewis Base Post-treatment

Muhammad Akmal Kamarudin; Daisuke Hirotani; Zhen Wang; Kengo Hamada; Kohei Nishimura; Qing Shen; Taro Toyoda; Satoshi Iikubo; Takashi Minemoto; Kenji Yoshino; Shuzi Hayase

doi:10.1021/acs.jpclett.9b02024

Suppression of Charge Carrier Recombination in Lead-Free Tin Halide Perovskite via Lewis Base Post-treatment

J Phys Chem Lett. 2019 Sep 5;10(17):5277-5283. doi: 10.1021/acs.jpclett.9b02024. Epub 2019 Aug 27.

Authors

Affiliations

¹ Info-Powered Energy System Research Center (i-PERC), The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.
² Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan.
³ Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 Japan.
⁴ Department of Electrical and Electronic Engineering, Faculty of Science and Engineering, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
⁵ Department of Electrical and Electronic Engineering, Miyazaki University, 1-1 Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan.

PMID: 31423786
DOI: 10.1021/acs.jpclett.9b02024

Abstract

Lead-free tin perovskite solar cells (PSCs) show the most promise to replace the more toxic lead-based perovskite solar cells. However, the efficiency is significantly less than that of lead-based PSCs as a result of low open-circuit voltage. This is due to the tendency of Sn²⁺ to oxidize into Sn⁴⁺ in the presence of air together with the formation of defects and traps caused by the fast crystallization of tin perovskite materials. Here, post-treatment of the tin perovskite layer with edamine Lewis base to suppress the recombination reaction in tin halide PSCs results in efficiencies higher than 10%, which is the highest reported efficiency to date for pure tin halide PSCs. The X-ray photoelectron spectroscopy data suggest that the recombination reaction originates from the nonstoichiometric Sn:I ratio rather than the Sn⁴⁺:Sn²⁺ ratio. The amine group in edamine bonded the undercoordinated tin, passivating the dangling bonds and defects, resulting in suppressed charge carrier recombination.