An Investigation on NiO for Hole Transport Material in Perovskite Solar Cells

Perovskite solar cells (PSCs) generally have charge transport materials for efficient and selective charge extraction. In PSCs, Spiro-OMeTAD has known as the greatest prominent hole transport material (HTM). Even so, the rising price of Spiro-OMeTAD attributable to the time and low-yielding synthetic process maintains a major obstacle to PSC commercialization. Recently, nickel oxide (NiO) as a versatile HTM for efficient PSCs has attracted particular attention due to its outstanding properties. Hence, this project aims to develop an electrode catalyst of NiO p-type as HTM as well as to characterize the properties of NiO. In this work, NiO was synthesized by nickel acetate precursors working along with the sol-gel spin coating approach. These films go on hardened at several temperatures of 400°C, 550°C, and 700°C and are characterized by different analytical techniques to study their morphological, structural, and optical properties using X-ray powder diffraction (XRD), UV-Vis spectroscopy, and Scanning electron microscopy (SEM). XRD and SEM results indicated that the crystalline quality of NiO was improved by increasing annealing temperature. The decrease in the bandgap energy from range 3.6 to 3.2 eV was observed upon increasing the annealing temperature from 400°C to 700°C. Based on these findings, NiO prepared at annealing temperature 700°C displayed the best properties hence it can be a good candidate as HTM in PSCs.