Saturation of Hysteretic Effect in Current–Voltage Characteristics of Perovskite Solar Cells

Abstract

The current–voltage characteristic curves of a perovskite solar cell (PSC) show a hysteretic effect. The effect is quantified as a hysteresis index (HI), which is a measure of the degree of hysteresis. The higher the value of the HI, the higher is the hysteretic effect. HI is determined by varying the thickness of the perovskite layer while keeping the interfacial layer constant and vice versa. It is observed that the value of the HI increases from 0.10 to 0.57 with increasing the thickness of the perovskite layer from 100 to 400 nm and saturates beyond 400 nm. In contrast, the value of HI is observed to remain constant at 0.57 over the entire variation of interfacial thickness. The observations are correlated with the number of trap‐states and ionic effects, inherently present in the perovskite and interface layers. The saturation of hysteretic effects beyond 400 nm is proposed to be due to the effective saturation of the screening effect produced by the mobile ions. The work highlights the combined role of trap‐states and ionic effects in controlling the hysteresis and provides an insight to optimize the PSCs to minimize the hysteretic effect, leading to a reliable power conversion efficiency.