Reducing Open-Circuit Voltage Losses in All-Inorganic Perovskite Cells by Dedoping
Zijian Peng, Jingjing Tian, Kaicheng Zhang, Albert These, Zhiqiang Xie, Yicheng Zhao, Andres Osvet, Fei Guo, Larry Lüer, Ning Li, Christoph J. Brabec
Abstract
CsPbI 2 Br is an attractive photovoltaic material due to its promising optoelectronic properties. However, the corresponding perovskite solar cells (PSCs) with p-i-n configuration suffer from low open-circuit voltage ( V OC ) and fill factor ( FF ), limiting their application in tandem solar cells. Here, we propose using the fullerene ICBA as the electron charge transporting layer (ETL), forming a better interfacial contact and enhancing the internal quasi-Fermi level splitting (QFLS). A further reduction of V OC losses of around 0.1 V was achieved by an ultrathin phenethylammonium chloride (PEACl) layer between the perovskite and the ETL. We precisely study the V OC improvement and find that passivation of surface recombination contributes only 20 mV, while more importantly, a major increase of 80 mV is achieved by dedoping the perovskite surface, which removes a non-negligible electron extraction barrier. Our results give helpful direction regarding how to further improve V OC in p-i-n perovskite cells.