Trace Doping: Fluorine-Containing Hydrophobic Lewis Acid Enables Stable Perovskite Solar Cells.

Abstract

With the rapid developments in perovskite solar cell (PSC), high efficiency has been achieved, but the long-term operational stability is still the most important challenges for the commercialization of this emerging photovoltaic technology. So far, bi-dopants Li-TFSI/t-BP doped hole-transporting materials (HTM) have led to state-of-the art efficiency in n-i-p PSCs. However, such dopants have several drawbacks in terms of stability, including the complex oxidation process, undesirable ion migration and ultra-hygroscopic nature. Herein, a fluorine-containing organic Lewis acid dopant bis(pentafluorophenyl)zinc (Zn-FP) with hydrophobic property and high migration barrier has been employed as a potential alternative to widely employedbi-dopants Li-TFSI/t-BP for PTAA. The resulting Zn-FP-based PSCs achieve a maximum PCE of 20.34% with J-V hysteresis-free. Specifically, the unencapsulated device exhibits significantly advancement of operational stability under the International Summit on Organic Photovoltaic Stability protocols (ISOS-L-1), maintaining over 90% of the original efficiency after operation for 1000 hours under continuous 1-sun equivalent illumination in N2 atmosphere in both forward and reverse J-V scan.