Interface Engineering for All-Inorganic CsPbI<sub>2</sub> Br Perovskite Solar Cells with Efficiency over 14.

Yan, Lei; Xue, Qifan; Liu, Meiyue; Zhu, Zonglong; Tian, Jingjing; Li, Zhenchao; Chen, Zhen; Chen, Ziming et al. · Adv Mater · 2018

basic_science · Level V

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Abstract

In this work, a SnO<sub>2</sub> /ZnO bilayered electron transporting layer (ETL) aimed to achieve low energy loss and large open-circuit voltage (V<sub>oc</sub> ) for high-efficiency all-inorganic CsPbI<sub>2</sub> Br perovskite solar cells (PVSCs) is introduced. The high-quality CsPbI<sub>2</sub> Br film with regular crystal grains and full coverage can be realized on the SnO<sub>2</sub> /ZnO surface. The higher-lying conduction band minimum of ZnO facilitates desirable cascade energy level alignment between the perovskite and SnO<sub>2</sub> /ZnO bilayered ETL with superior electron extraction capability, resulting in a suppressed interfacial trap-assisted recombination with lower charge recombination rate and greater charge extraction efficiency. The as-optimized all-inorganic PVSC delivers a high V<sub>oc</sub> of 1.23 V and power conversion efficiency (PCE) of 14.6%, which is one of the best efficiencies reported for the Cs-based all-inorganic PVSCs to date. More importantly, decent thermal stability with only 20% PCE loss is demonstrated for the SnO<sub>2</sub> /ZnO-based CsPbI<sub>2</sub> Br PVSCs after being heated at 85 °C for 300 h. These findings provide important interface design insights that will be crucial to further improve the efficiency of all-inorganic PVSCs in the future.