Methylamine Vapor Exposure for Improved Morphology and Stability of Cesium-Methylammonium Lead Halide Perovskite Thin-Films

TL;DR

This study investigates how methylamine vapor exposure enhances the morphology and stability of cesium-methylammonium lead halide perovskite thin-films, leading to improved lifetime and stability in ambient conditions for solar cell applications.

Contribution

It provides a systematic analysis of cesium incorporation effects and introduces methylamine vapor exposure as a method to improve film stability and orientation.

Findings

Mixed-cation films show higher stability after ambient exposure.

Methylamine vapor treatment increases film orientation and stability.

Cs0.10MA0.90PbI2.90Br0.10 films achieve nearly 50 microseconds lifetime after 9 hours.

Abstract

Mixed-cation Cesium-Methylammonium lead halide perovskite (CsxMA1-xPbI3-xBrx) thin-films have been used to demonstrate stable and efficient perovskite devices. However, a systematic study of the Cs incorporation on the properties of the perovskite films has not been reported. In this report, Impact of Cesium incorporation on the minority carrier recombination lifetime of Cesium-Methylammonium lead halide perovskite thin-films is studied. The lifetime for the as-deposited perovskite films decreases with increasing concentration of cesium. However, mixed cation perovskite film is more stable, showing higher lifetime (15-20 micro seconds) after 9 hours of ambient exposure than just after deposition (6-13 micro seconds). Methylamine Vapor Exposure (MVE) technique was used to improve the morphology of the as-deposited film. MVE treated films are more oriented along (110) direction and were even more stable in ambient, with Cs0.10MA0.90PbI2.90Br0.10 films showing lifetime of almost 50 micro seconds after 9 hours of ambient exposure, twice the lifetime of a comparable MAPbI3 film. These results throw light on why mixed-cation cesium-methylamine lead halide perovskite films are better for highly efficient and stable perovskite solar cells.