Chen, Chun-Hao; Su, Zhen-Huang; Lou, Yan-Hui; Yu, Yan-Jun; Wang, Kai-Li; Liu, Gen-Lin; Shi, Yi-Ran; Chen, Jing; Cao, Jun-Jie; Zhang, Liang; Gao, Xing-Yu; Wang, Zhao-Kui

ADVANCED MATERIALS

2022, 34, 0935-9648

Chen, Chun-Hao; Su, Zhen-Huang; Lou, Yan-Hui; Yu, Yan-Jun; Wang, Kai-Li; Liu, Gen-Lin; Shi, Yi-Ran; Chen, Jing; Cao, Jun-Jie; Zhang, Liang; Gao, Xing-Yu; Wang, Zhao-Kui

Perovskite photovoltaics are strong potential candidates to drive low-power off-grid electronics for indoor applications. Compared with rigid devices, flexible perovskite devices can provide a more suitable surface for indoor small electronic devices, enabling them have a broader indoor application prospect. However, the mechanical stability of flexible perovskite photovoltaics is an urgent issue solved. Herein, a kind of 3D crosslinking agent named borax is selected to carry out grain boundary penetration treatment on perovskite film to realize full-dimensional stress release. This strategy improves the mechanical and phase stabilities of perovskite films subjected to external forces or large temperature changes. The fabricated perovskite photovoltaics deliver a champion power conversion efficiency (PCE) of 21.63% under AM 1.5G illumination, which is the highest one to date. The merit of low trap states under weak light makes the devices present a superior indoor PCE of 31.85% under 1062 lux (LED, 2956 K), which is currently the best flexible perovskite indoor photovoltaic device. This work provides a full-dimensional grain boundary stress release strategy for highly stable flexible perovskite indoor photovoltaics.