Cathode modification with solution-processed hybrid electron extraction layer for improved charge collection of planar heterojunction perovskite solar cells

Abstract

Abstract Optimal interface modification of perovskite solar cells is critical to achieve efficient and balanced charge transport and collection. We herein demonstrated that a solution-processed hybrid cathode interfacial layer composed of polyetyleneimine ethoxylate and a lithium quinolate complex improves photovoltaic performance of the planar heterojunction perovskite solar cells. The hybrid cathode modifier effectively lowered work function of ITO cathode, which afforded efficient electron transport and collection at ITO. Furthermore, surface roughness of ITO was significantly decreased, leading to enlarged grain size in densely-packed perovskite thin film. Consequently, the perovskite solar cells with hybrid electron extraction layer generated maximum power conversion efficiency up 15.21%, which is 25% improved value than that without hybrid electron extraction layer. Furthermore, highly-flexible flexible devices with a hybrid electron extraction layer exhibited a promising efficiency of 14.41%, demonstrating its potential for high performance perovskite solar cells.