Effect of NiO Precursor Solution Ageing on the Perovskite Film Formation and Their Integration as Hole Transport Material for Perovskite Solar Cells.

Exceptional progress in the performance of perovskite solar cells in a very short time has made it a potential photovoltaic technology for future deployment. The compositional engineering in perovskite materials and other buffer layers makes it a feasible candidate for commercial applications in the near future. However, there are certain challenges associated with these devices which need to be addressed such as device stability, process dependent device efficiency, hole transport layer (HTL) etc. The device performance is highly dependent on the processing parameters of the precursors. Understanding the origin of this challenge is very crucial for reproducible device performance. In this work, we have focused on utilizing NiO as a HTL in planar perovskite solar cells and studied the ageing effect of NiO precursor solution on the perovskite film quality in terms of crystallinity, grain growth, surface morphology, and overall device performance. It is observed that the ageing of NiO precursor promotes the formation of NiO films with increased roughness which improves the perovskite film quality. Structural and morphological studies revealed that the perovskite films formed on aged NiO films were highly crystalline in nature, uniform and with larger grain size. Current- voltage characteristics under illumination show that the films casted from NiO aged solution are better for perovskite solar cell applications and result in reduced parasitic resistances and enhanced charge transport.