High‐Performance Planar Perovskite Solar Cells Using Low Temperature, Solution–Combustion‐Based Nickel Oxide Hole Transporting Layer with Efficiency Exceeding 20%

Abstract NiO x hole transporting layer has been extensively studied in optoelectronic devices. In this paper, the low temperature, solution–combustion‐based method is employed to prepare the NiO x hole transporting layer. The resulting NiO x thin films show better quality and preferable energy alignment with perovskite thin film compared to high temperature sol–gel‐processed NiO x . With this, high‐performance perovskite solar cells are fabricated successfully with power conversion efficiency exceeding 20% using a modified two‐step prepared MA 1− y FA y PbI 3− x Cl x perovskite. This efficiency value is among the highest values for NiO x ‐based devices. Various characterizations and analyses provide evidence of better film quality, enhanced charge transport and extraction, and suppressed charge recombination. Meanwhile, the device exhibits much better device stability compared to sol–gel‐processed NiO x and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐based devices.