Surface defect passivation by copper incorporation for efficient perovskite solar cells

Defects play an important character in the degradation processes of hybrid halide perovskite, hindering their application for solar cells. Ion transport is facilitated by the ubiquitous organic cation and halide anion vacancy defects, which lead to perovskite disintegration at grain boundaries. In this article, a thorough investigation of the vacancy defect and defect density on perovskite is conducted by using VASP and SCAPS-1D. From SCAPS-1D, the PCE of the device increases from 17.82 % to 23.04 % when the defect state density drops from 10 ⁺¹⁵ to 10 ⁺¹⁴ cm ^-3 . Therefore, reducing the defect density is very important to improve the performance of perovskite solar cells. Effective perovskite solar cells based on CH ₃NH ₃PbI ₃ incorporated copper ions passivation defects were carried out. Compare to pristine hybrid perovskite, Cu ²⁺-doped hybrid perovskite have remarkably lower trap-state densities, greater film quality, and higher crystallinity. Especially, the maximum power conversion efficiency of up to 20.1 % was achieved with 0.5 % copper ion doping. After 500 h of not being enclosed in dry air, the devices still has 87 % of its original power conversion efficiency. Therefore, this work suggests that careful control the formation of Cu ²⁺ in perovskite films is very important for diverse optoelectronic applications in the future.