Nickel oxide hole transport layer for perovskite solar cells: Preparation via pulsed laser deposition with simulation and experimental insights

Abstract

Nickel oxide (NiOx) has gained attention as a promising inorganic hole transport layer for perovskite solar cells due to its wide bandgap, high transparency, and stability. However, tuning of band alignment by an extra dipole layer is necessary to achieve high efficiencies. Our predictive simulations suggest that NiOx bandgap tuning can also improve solar cell performance. Motivated by these findings, this study experimentally investigates NiOx films with different bandgap fabricated using pulsed laser deposition under varying deposition conditions, including oxygen pressure, substrate temperature and laser frequency. Our outcomes show that mainly the deposition temperature significantly influences the chemical composition, optical properties, and defect states in the NiOx films, lattice constants and morphology as confirmed by X-ray photoelectron spectroscopy, photothermal deflection spectroscopy, X-ray diffraction spectroscopy, atomic force microscopy and scanning electron microscopy. Experimentally, FA0.83Cs0.17Pb(I0.6Br0.4)3 mixed halide perovskite solar cells were fabricated on NiOx substrates prepared under varying oxygen pressures and pulse numbers, achieving a maximum power conversion efficiency of approximately 8 %. This demonstrates that NiOx deposited by pulsed laser deposition, when properly tuned, is a promising candidate for an efficient hole transport layer in perovskite-based photovoltaics.