Enhanced Performance of Inverted Perovskite Solar Cells Employing NiOx and Cu-Doped NiOx Nanoparticle Hole Transport Layers

In this study, p-type NiOx and Cu-doped NiOx nanoparticles (NPs) were synthesized by a simple chemical precipitation method and used as hole transport layers (HTLs) for inverted perovskite solar cells (PSCs). The microstructural property, surface morphology, elemental composition, optical property, charge recombination, and surface topography of the NiOx and Cu-NiOx HTLs were comprehensively characterized. The results showed that the NiOx and Cu-NiOx NPs were uniformly coated on the substrates without pinholes or voids. Cu incorporation into NiOx did not change its crystalline nature and considerably improved its electrical conductivity. The Cu-NiOx HTLs exhibited superior photoluminescence quenching and the least lifetime decay, which indicated that Cu-NiOx exhibited higher charge transport than NiOx HTLs. The fabricated PSC performances were further analyzed using current density–voltage characteristics, external quantum efficiency, and electrochemical impedance spectroscopy. The PSCs with PEDOT:PSS, NiOx, and 2% Cu-NiOx HTLs exhibited power conversion efficiencies of 11.93%, 13.72%, and 15.54%, respectively. The 2% Cu-NiOx HTL-based device showed the best performance compared with the PEDOT:PSS- and NiOx-based devices. Academic Editors: Chunyang Zhang, Dou Zhang