Physics, Simulation, and Experiment of Perovskite Solar Cells with Addressing Hysteresis Effect

The hysteresis effect is a critical factor affecting the widespread application of perovskite solar cells (PSCs). To eliminate this adverse effect, it is necessary to uncover the underlying physics, which characterize the microscopic behaviors of electrons, holes, and ions within PSCs. Herein, addressing the hysteresis effect of PSCs, the migration mechanisms of mobile ions (i.e., anions and cations) within the perovskite layer is explored, the simulation model is developed, and the corresponding experiments are performed. The electromagnetic response, the transport of electrons, holes, anions, and cations, and the electrostatic characteristics determined by the charges are considered in detail. The simulation verifies that the performance degradation is indeed originating from the mobile ions, especially under a high ion concentration. The physical reason of the unbalanced performance under forward and reverse electric scans is presented by optoelectronic simulation. The manipulation of the hysteresis effect increasing the built-in electric field and reducing the hysteresis index (HI) of low ion concentration devices, but increased HI under a high ion concentration is further investigated. The simulation guides the fabrication of a normal-bandgap PSC, which achieves the reverse (forward) power-conversion efficiency up to 23.35% (22.22%) with a HI as low as 4.8%.