Strong-bonding hole-transport layers reduce ultraviolet degradation of perovskite solar cells.

Chengbin Fei Anastasia Kuvayskaya Xiaoqiang Shi Mengru Wang Zhifang Shi Haoyang Jiao Timothy J Silverman Michael Owen-Bellini Yifan Dong Yeming Xian Prashant V Kamat Xiaoming Wang Guang Yang Hangyu GuNengxu LiConnor J Dolan Zhewen J D Deng Deniz N Cakan David P Fenning Yanfa Yan Matthew C Beard Laura T Schelhas Alan Sellinger Jinsong Huang

Published in: Science (New York, N.Y.) (2024)

The light-emitting diodes (LEDs) used in indoor testing of perovskite solar cells do not expose them to the levels of ultraviolet (UV) radiation that they would receive in actual outdoor use. We report degradation mechanisms of p-i-n-structured perovskite solar cells under unfiltered sunlight and with LEDs. Weak chemical bonding between perovskites and polymer hole-transporting materials (HTMs) and transparent conducting oxides (TCOs) dominate the accelerated A-site cation migration, rather than direct degradation of HTMs. An aromatic phosphonic acid, [2-(9-ethyl-9H-carbazol-3-yl)ethyl]phosphonic acid (EtCz3EPA), enhanced bonding at the perovskite/HTM/TCO region with a phosphonic acid group bonded to TCOs and a nitrogen group interacting with lead in perovskites. A hybrid HTM of EtCz3EPA with strong hole-extraction polymers retained high efficiency and improved the UV stability of perovskite devices, and a champion perovskite minimodule-independently measured by the Perovskite PV Accelerator for Commercializing Technologies (PACT) center-retained operational efficiency of >16% after 29 weeks of outdoor testing.

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