Compositional Engineering for Thermally Stable, Highly Efficient Perovskite Solar Cells Exceeding 20% Power Conversion Efficiency with 85 °C/85% 1000 h Stability.

Matsui, Taisuke; Yamamoto, Teruaki; Nishihara, Takashi; Morisawa, Ryosuke; Yokoyama, Tomoyasu; Sekiguchi, Takashi; Negami, Takayuki · Adv Mater · 2019

basic_science · Level V

Where this comes from

Abstract

Perovskite solar cells have received great attention because of their rapid progress in efficiency, with a present certified highest efficiency of 23.3%. Achieving both high efficiency and high thermal stability is one of the biggest challenges currently limiting perovskite solar cells because devices displaying stability at high temperature frequently suffer from a marked decrease of efficiency. In this report, the relationship between perovskite composition and device thermal stability is examined. It is revealed that Rb can suppress the growth of PbI<sub>2</sub> even under PbI<sub>2</sub> -rich conditions and decreasing the Br ratio in the perovskite absorber layer can prevent the generation of unwanted RbBr-based aggregations. The optimized device achieved by engineering perovskite composition exhibits 92% power conversion efficiency retention in a stress test conducted at 85 °C/85% relative humidity (RH) according to an international standard (IEC 61215) while exceeding 20% power conversion efficiency (certified efficiency of 20.8% at 1 cm<sup>2</sup> ). These results reveal the great potential for the practical use of perovskite solar cells in the near future.