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

Abstract

Practical implementation of hybrid perovskite solar cells (PSCs) depends on achieving decent lifetimes under realistic operational conditions. The degradation pathways in PSCs are effectively mitigated using charge-transport interlayers, which are usually designed based on empiric considerations. Herein, we present a systematic comparative study of a series of hole-transport materials for p−i−n perovskite solar cells such as CuI, CuSCN, MnS, CuO x , MoO x , VO x , WO x , and PTAA and reveal their influence on the light-induced degradation of MAPbI 3 as a model perovskite absorber material. Using a set of complementary techniques, we demonstrate that WO x enables the best stack stability, while CuO x , on the contrary, strongly facilitates the degradation of the perovskite material 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 perovskite absorber and, hence, could not form efficient hole-extraction layers in p−i−n perovskite solar cells. The obtained results provide important guidelines for the rational design of hole-transport materials for perovskite solar cells and feature the most promising candidates, which could enable the long-term operational stability of PSCs.

Impact of hole-transport layer materials on the field-induced degradation of p-i-n perovskite solar cells

“…1) included poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), which was reported to improve photostability of PSCs, 33,34 poly(ethylene-3,4-dioxythiophene):polystyrenesulfonate (PEDOT:PSS), which was one of the first used hole-selective interlayers for p-i-n PSCs, 35 inorganic NiO x representing a widely used hole-transport material for scalable fabrication of PSCs, 36 and the PTAA/NiO x hybrid, which showed very promising performances in PSCs. 34,37,38 All our bias exposure and device characterization experiments were performed in the dark at room temperature inside a glovebox with a well-controlled anoxic atmosphere (O 2 , H 2 O <0.1 ppm) for establishing the effect of electric field on the HTM in the absence of any other internal (heat and light) or external (moisture and oxygen) stress factors.…”