Comprehensive study of anomalous hysteresis behavior in perovskite-based solar cells.

Perovskite solar cells (PSCs) have shown remarkable progress with the rapid increase in power conversion efficiency to reach 25.7% over the last few years. However, it is difficult to precisely determine the energy conversion efficiency for PSC, because of anomalous current density-voltage (J-V) hysteresis. Normal J-V hysteresis has been reported in many papers, where the backward scan performance is higher than the forward scan one. In this work, using Drift-Diffusion Modeling, normal hysteretic behavior associated with ion migration with different scanning rates, pre-bias voltages, and charge-carrier mobility is studied. In addition, the inverted J-V hysteresis by modification of the simulation model, where anions and cations flux towards the transport layers and are accumulated simultaneously on both sides, is achieved. It is also found that the flux parameter values (gae and gch) play a critical role in the reduction of inverted hysteresis and the efficiency enhancement. It is suggested from the current studies that perovskite interfaces encapsulation, which prevents ions migration, could be of great importance for achieving hysteresis-free PSCs and reliable device characteristics.