Enhancing perovskite solar cell performance: Investigating the impact of post-annealing on the optoelectrical and structural properties of RF-sputtered NiO films via SCAPS-1D device modeling

In recent years, perovskite solar cells have garnered significant interest in the field of solar cell research and development, primarily due to their notable efficiency. However, their limited lifespan and material defects, particularly in the interface layer and during deposition or fabrication processes, pose challenges to their widespread adoption. Innovative approaches to material processing and design are essential to addressing these issues. This paper introduces a novel method for the deposition of nickel oxide (NiO) thin films aimed at enhancing the performance of perovskite solar cells. Our study involved depositing NiO films on glass substrates using an optimised RF magnetron sputtering process at room temperature. These films were then annealed at temperatures ranging from 100 to 400 °C in an open-air setting. X-ray diffraction analysis showed that pure NiO thin films were formed. These films had a cubic crystalline structure and were mostly oriented along the (200) plane. Crucially, annealing at 100 °C significantly improved the crystallinity of the NiO films, reducing the average crystallite size from 21.05 to 6.10 nm, as evidenced by field emission scanning electron microscopy. For solar cells, this kind of microstructural refinement is very important because it changes the optical band gap, which ranged from 3.81 to 3.86 eV depending on the annealing temperature, and it also has a big effect on the films' electrical properties. The outstanding electrical characteristics of the NiO film annealed at 100 °C are particularly remarkable. We used these improved NiO films in perovskite solar cells that had a structure of FTO/NiO/MAPbI3/PCBM/Ag and ran SCAPS-1D simulations to see how well they worked. The simulation results are promising, indicating an enhancement in cell efficiency with the potential to surpass 22 %. This advancement highlights the critical role of advanced thin film deposition techniques in advancing photovoltaic technology and marks a substantial step towards unlocking the full potential of perovskite solar cells.