Enhanced Performance of Perovskite Solar Cells with Zinc Chloride Additives.

Perovskite solar cells (PSCs) have attracted extensive attention due to their impressive photovoltaic performance. The quality of the perovskite layer is very critical to achieve high device performance. Here, we explore the partial substitution of PbI2 by ZnCl2 in the preparation of CH3NH3PbI3 and its effects on perovskite morphology, optical properties, and photovoltaic performance. Consequently, the device with 3% ZnCl2 shows great improvement in power conversion efficiency (PCE) from 16.4 to 18.2% compared to that of the control device. Moreover, the device is more stable than the control device, with only 7% degradation after aging for 30 days. These results are attributed to the increased grain size, improved film morphology, and reduced recombination loss after the partial substitution of PbI2 by ZnCl2 in the perovskite film. This work develops a new approach for morphology control through rational additives in the perovskite film, and paves the way toward further enhancing the device performances of PSCs including PCE and stability.