Perovskite Grains Embraced in a Soft Fullerene Network Make Highly Efficient Flexible Solar Cells with Superior Mechanical Stability.

Li, Meng; Yang, Ying-Guo; Wang, Zhao-Kui; Kang, Tin; Wang, Qiong; Turren-Cruz, Silver-Hamill; Gao, Xing-Yu; Hsu, Chain-Shu et al. · Adv Mater · 2019

basic_science · Level V

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Abstract

Halide perovskite films processed from solution at low-temperature offer promising opportunities to make flexible solar cells. However, the brittleness of perovskite films is an issue for mechanical stability in flexible devices. Herein, photo-crosslinked [6,6]-phenylC<sub>61</sub> -butyric oxetane dendron ester (C-PCBOD) is used to improve the mechanical stability of methylammonium lead iodide (MAPbI<sub>3</sub> ) perovskite films. Also, it is demonstrated that C-PCBOD passivates the grain boundaries, which reduces the formation of trap states and enhances the environmental stability of MAPbI<sub>3</sub> . Thus, MAPbI<sub>3</sub> perovskite solar cells are prepared on solid and flexible substrates with record efficiencies of 20.4% and 18.1%, respectively, which are among the highest ever reported for MAPbI<sub>3</sub> on both flexible and solid substrates. The result of this work provides a step improvement toward stable and efficient flexible perovskite solar cells.