New insight on the open-circuit voltage of perovskite solar cells: The role of defect-density distribution and electric field in the active layer

In this article, we study the J–V characteristic of a perovskite solar cell (PSC) prepared by the two-step method. PSCs were fabricated by methylammonium lead iodide using the sequential deposition method. We describe J–V curves using a modified dynamic electrical model based on an asymmetric electric field. In addition, we simulated the PSCs by solar cell capacitance simulator package to investigate the role of trap-density distribution in cell performance. The experimentally optimized device shows an enhancement in the open-circuit voltage (V_OC) from 1.08 to 1.21 V. Simulation results show that the increase in V_OC up to 1.15 V is corresponding to a trap-density of 2.38×10¹⁵ cm⁻³. However, these results predict that a decrease in the trap-density can increases the V_OC and FF up to 1.19 V and 79% while the modified dynamic electrical model gives the J–V characteristic as well as experimental results. Our results suggest that the increase in V_OC can be attributed to the asymmetric electric field at the interface of the perovskite layer.