Multifunctional Polymer-Regulated SnO<sub>2</sub> Nanocrystals Enhance Interface Contact for Efficient and Stable Planar Perovskite Solar Cells.

You, Shuai; Zeng, Haipeng; Ku, Zhiliang; Wang, Xiaoze; Wang, Zhen; Rong, Yaoguang; Zhao, Yang; Zheng, Xin et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

Perovskite solar cells (PSCs) have rapidly developed and achieved power conversion efficiencies of over 20% with diverse technical routes. Particularly, planar-structured PSCs can be fabricated with low-temperature (≤150 °C) solution-based processes, which is energy efficient and compatible with flexible substrates. Here, the efficiency and stability of planar PSCs are enhanced by improving the interface contact between the SnO<sub>2</sub> electron-transport layer (ETL) and the perovskite layer. A biological polymer (heparin potassium, HP) is introduced to regulate the arrangement of SnO<sub>2</sub> nanocrystals, and induce vertically aligned crystal growth of perovskites on top. Correspondingly, SnO<sub>2</sub> -HP-based devices can demonstrate an average efficiency of 23.03% on rigid substrates with enhanced open-circuit voltage (V<sub>OC</sub> ) of 1.162 V and high reproducibility. Attributed to the strengthened interface binding, the devices obtain high operational stability, retaining 97% of their initial performance (power conversion efficiency, PCE > 22%) after 1000 h operation at their maximum power point under 1 sun illumination. Besides, the HP-modified SnO<sub>2</sub> ETL exhibits promising potential for application in flexible and large-area devices.