Surface chelation of cesium halide perovskite by dithiocarbamate for efficient and stable solar cells

Shuang Yang,Hua Gui Yang,Jingjing He,Yu Hou,Yun Wang,Junxian Liu

doi:10.1038/s41467-020-18015-5

Shuang Yang, Hua Gui Yang + Show 4 more

Open Access

https://doi.org/10.1038/s41467-020-18015-5

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Abstract

Surface engineering has been shown critical for the success of perovskite solar cells by passivating the surface enriched defects and mobile species. The discovery of surface modulators with superior interaction strength to perovskite is of paramount importance since they can retain reliable passivation under various environments. Here, we report a chelation strategy for surface engineering of CsPbI2Br perovskite, in which dithiocarbamate molecules can be coordinate to surface Pb sites via strong bidentate chelating bonding. Such chelated CsPbI2Br perovskite can realize excellent passivation of surface under-coordinated defects, reaching a champion power conversion efficiency of 17.03% and an open-circuit voltage of 1.37 V of CsPbI2Br solar cells. More importantly, our chelation strategy enabled excellent device stability by maintaining 98% of their initial efficiency for over 1400 h in ambient condition. Our findings provide scientific insights on the surface engineering of perovskite that can facilitate the further development and application of perovskite optoelectronics.

Highlights

Surface engineering has been shown critical for the success of perovskite solar cells by passivating the surface enriched defects and mobile species
Among various cesium halide perovskites, CsPbI2Br perovskite is considered to be a good candidate for the high efficiency and stable all-inorganic perovskite solar cells (PSCs) due to its reasonable Goldschmidt tolerance factor and the lower phase transition temperature with band gaps between 1.82 and 1.92 eV12,13
The theoretical results based on the density functional theory (DFT) reveal that the Pb(DDTC)[2] is adsorbed strongly on the surface with an adsorption energy of −1.73 eV, which is much larger than that of the prevalent passivation molecules, such as ammoniums or carboxylic acids of about −0.4 and −0.3 eV32,33

Summary

Introduction

Surface engineering has been shown critical for the success of perovskite solar cells by passivating the surface enriched defects and mobile species. We report a chelation strategy for surface engineering of CsPbI2Br perovskite, in which dithiocarbamate molecules can be coordinate to surface Pb sites via strong bidentate chelating bonding. Such chelated CsPbI2Br perovskite can realize excellent passivation of surface under-coordinated defects, reaching a champion power conversion efficiency of 17.03% and an open-circuit voltage of 1.37 V of CsPbI2Br solar cells. It was found that DDTC molecule strongly coordinates to surface Pb cation of perovskite via a bidentate chelating bonding Such chelating structure enabled excellent and persistent passivation of surface defects of CsPbI2Br perovskite, generating significantly enhanced efficiency of 17.02% for CsPbI2Br solar cells as well as increased humidity and irradiation stability

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