Benchmarking the Stability of Hole-Transport Materials for p-i-n Perovskite Solar Cells: The Importance of Interfacial Reactions

Practicalimplementation of hybrid perovskite solar cells (PSCs)depends on achieving decent lifetimes under realistic operationalconditions. The degradation pathways in PSCs are effectively mitigatedusing charge-transport interlayers, which are usually designed basedon empiric considerations. Herein, we present a systematic comparativestudy of a series of hole-transport materials for p-i-nperovskite solar cells such as CuI, CuSCN, MnS, CuO (x) , MoO (x) , VO (x) , WO (x) , and PTAA and reveal theirinfluence on the light-induced degradation of MAPbI(3) asa model perovskite absorber material. Using a set of complementarytechniques, we demonstrate that WO (x) enablesthe best stack stability, while CuO (x) ,on the contrary, strongly facilitates the degradation of the perovskitematerial due to the formation of PbO and other aging products. Furthermore,we show that such materials as CuO (x) , CuI,and CuSCN undergo severe intermixing with the deposited above perovskiteabsorber and, hence, could not form efficient hole-extraction layersin p-i-n perovskite solar cells. The obtained resultsprovide important guidelines for the rational design of hole-transportmaterials for perovskite solar cells and feature the most promisingcandidates, which could enable the long-term operational stabilityof PSCs.