Effect of defect density and energy level mismatch on the performance of perovskite solar cells by numerical simulation

The defects at the absorber and interface layer of organic-inorganic lead halide perovskite solar cells are unfavorable for efficiency as well as the stability. In this study, we have performed the numerical simulation on inverted planar structure perovskite solar cell based on NiO as a hole transport material (HTM) by SCAPS ^-1 D. Here we investigated the effects of defect density and energy level of the perovskite absorber layer and perovskite/HTM interface layer on the performance, respectively. The analysis revealed that values of J _sc , V _oc , and FF of perovskite solar cells are significantly reduced with increasing the defect density of perovskite layer. The power conversion efficiency severely reduced from 25 to 5% when the defect density increased from 10 ¹³ to 10 ¹⁸ cm ⁻³ , respectively. A similar trend was also found in case of interfacial defect between Perovskite and HTM layer. It was found that the defect energy level more than 0.3 eV above conduction band of perovskite has almost no detrimental effect on the device's efficiency.