Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells

TL;DR

This study compares organic-inorganic and all-inorganic lead bromide perovskites, demonstrating that cesium-based devices exhibit superior long-term stability while maintaining comparable efficiency to methyl ammonium-based solar cells.

Contribution

It provides a direct comparison of MAPbBr3 and CsPbBr3 perovskites, highlighting cesium's role in enhancing thermal stability and device longevity without sacrificing performance.

Findings

CsPbBr3 has higher thermal stability than MAPbBr3.

Both perovskites achieve ~6% efficiency under standard illumination.

CsPbBr3 devices remain stable after 2 weeks of aging under various conditions.

Abstract

Direct comparison between perovskite-structured hybrid organic-inorganic - methyl ammonium lead bromide (MAPbBr3) and all-inorganic cesium lead bromide (CsPbBr3), allows identifying possible fundamental differences in their structural, thermal and electronic characteristics. Both materials possess a similar direct optical band-gap, but CsPbBr3 demonstrates a higher thermal stability than MAPbBr3. In order to compare device properties we fabricated solar cells, with similarly synthesized MAPbBr3 or CsPbBr3, over mesoporous titania scaffolds. Both cell types demonstrated comparable photovoltaic performances under AM1.5 illumination, reaching power conversion efficiencies of ~6 % with a poly-aryl amine-based derivative as hole transport material. Further analysis shows that Cs-based devices are as efficient as, and more stable than methyl ammonium-based ones, after aging (storing the cells for 2 weeks in a dry (relative humidity 15-20%) air atmosphere in the dark) for 2 weeks, under constant illumination (at maximum power), and under electron beam irradiation.