SONG Yan-Lin lab together with Prof. Wang Yang from the Institute of Chemistry of the Chinese Academy of Sciences, along with their collaborators, have proposed the molecule triggered strain regulation and interfacial passivation strategy, achieving the perovskite strain regulation, interface passivation and the enhancement of efficiency and stability of devices (especially UV light stability).

Researchers utilized the [2+2] cycloadditions reaction (the photo-induced [2+2] reaction triggered by UV 365 nm irradiation and photo-cleavage of the cross-link with UV 254 nm) of 6-Bromocoumarin-3-carboxylic acid ethyl ester (BAEE) to perovskite strain regulation for releasing residual tensile strain, meanwhile, -Br and carbonyl groups of BAEE molecule efficiently passivated I vacancy defects of perovskite.

The BAEE-perovskite film exhibited the remarkable UV light stability and obviously released the tensile stress slightly decreased from 24.3 Mpa to 18.2 Mpa. The efficiency of BAEE-PSC was up to 26.32% with high open-circuit voltage 1.201 V and low Voc loss (0.342 V). Furthermore, the unencapsulated BAEE-PSCs retained 90% of their initial efficiency under continuous 365 nm UV illumination: T₉₀ > 110 h in N₂, T₉₀ > 6 h in ambient air and continuous LED white light irradiation at 100 mWcm^-2: T₉₀ > 1000 h.

This work has been published in Joule. The research was supported by the National Natural Science Foundation of China, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, the National Key R&D Program of China, and the Beijing National Laboratory for Molecular Sciences.

Contact:

Prof. SONG Yanlin

Institute of Chemistry, Chinese Academy of Sciences

Email: ylsong@iccas.ac.cn