CuCrO₂ nanoparticles incorporated into ptaa as a hole transport layer for 85^◦ c and light stabilities in perovskite solar cells

High-mobility inorganic CuCrO₂ nanoparticles are co-utilized with conventional poly(bis(4-phenyl)(2,5,6-trimethylphenyl)amine) (PTAA) as a hole transport layer (HTL) for perovskite solar cells to improve device performance and long-term stability. Even though CuCrO₂ nanoparticles can be readily synthesized by hydrothermal reaction, it is difficult to form a uniform HTL with CuCrO₂ alone due to the severe agglomeration of nanoparticles. Herein, both CuCrO₂ nanoparticles and PTAA are sequentially deposited on perovskite by a simple spin-coating process, forming uniform HTL with excellent coverage. Due to the presence of high-mobility CuCrO₂ nanoparticles, CuCrO₂ /PTAA HTL demonstrates better carrier extraction and transport. A reduction in trap density is also observed by trap-filled limited voltages and capacitance analyses. Incorporation of stable CuCrO₂ also contributes to the improved device stability under heat and light. Encapsulated perovskite solar cells with CuCrO₂ /PTAA HTL retain their efficiency over 90% after ~900-h storage in 85^◦ C/85% relative humidity and under continuous 1-sun illumination at maximum-power point.