Effect of Voids Within Copper Iodine Hole Transport Layer Using the Ethanol/Iodine Solution Method in Inverted Planar Perovskite Solar Cells

This paper aims to present the effect of voids within a copper iodine (CuI) hole transport layer (HTL) using the ethanol/iodine solution method for inverted planar perovskite solar cells. The $\text{CuI}$ layer was fabricated from copper nitride $(\text{Cu}_{3}\mathrm{N})$ thin film by RF magnetron sputtering and iodization using the iodine/ethanol solution. The results demonstrated a power conversion efficiency (PCE) of 1.71 % with a short-circuit current density $(J_{\text{SC}})$ of 4.76 mA/cm2 and an open-circuit voltage $(V_{\text{OC}})$ of 0.54 V was achieved. The low performance of the cell is due to voids obtained within the CuI layer, which allow the perovskite layer to make direct contact with the ITO layer. Additionally, voids within the CuI layer create a large interface area between the perovskite and CuI layers, which affects high recombination and low cell performance.