Enhancing efficiency and stability of inverted structure perovskite solar cells with fullerene C60 doped PC61BM electron transport layer

[6, 6]-phenyl C61butyric acid methyl ester (PC61BM) is a common fullerene derivative widely employed as an electron transport layer in inverted perovskite solar cells. However, major challenges such as interfacial recombination, current leakage and low mobility results in poor photovoltaic performance and stability for PC61BM-based devices. To overcome these issues, we demonstrated, for the first time, doping of the PC61BM with fullerene C60 to tailor the properties of the PC61BM. This doping approach helped to realize superior power conversion efficiency of perovskite solar cell with 17.46% versus pristine device with 14.20%. The C60 doped PC61BM reinforced the surface morphology of the PC61BM layer with reduced roughness and better coverage, up-shift of Fermi Level, higher electrical conductivity, higher maximum charge carrier generation rate, and higher charge collection probability. All these improvements contributed to reduced charge leakage at the interface, reduced charge recombination and promoted efficient charge transfer, transport, and collection. Furthermore, the enhanced hydrophobicity of the C60 doped PC61BM enabled superior ambient device stability compared to the pristine device. This work facilitates a simple and effective route to tailor perovskite solar cell performance towards higher efficiency and better stability.