The effect of perovskite interface contacts on hysteresis behavior in perovskite solar cells

The ionic-electronic drift-diffusion model is employed to simulate the hysteresis behavior in perovskite solar cells (PSCs) under low-to-moderate conditions; the migrating ions stop at the HTL/ETL interfaces. However, for high-applied bias voltage, illumination, air exposure for weeks, and special cell configuration, these ions can also reach the external contact interfaces, presenting anomalous hysteresis behavior. This has already been confirmed experimentally but has not been modeled yet. The ion flux toward contacts has been considered in our model by introducing new parameters, such as boundary absorption velocity for anions and cations (Q_a,c). The results comprise low hysteresis in the J-V characteristic by an increase in the boundary absorption velocity. Moreover, by increasing the scanning time (low scan rate), ions have enough time to reach the ETL/contact and HTL/contact interfaces, which leads to enhanced and inverted hysteresis and decreased efficiency. Finally, a unique and optimized set of material parameters, mainly related to ion migration parameters, has been achieved. Therefore, the cell efficiency is enhanced from 16.47 to 26.38% by using the optimized parameters. Our results show that ion migration prevention has an essential role in producing highly efficient, hysteresis-free, and stable solar cells that are ready for real-world applications.