The Effect of Energy Level of Transport Layer on the Performance of Ambient Air Prepared Perovskite Solar Cell: A SCAPS-1D Simulation Study

Abstract

The perovskite solar cell (PSC) as an emerging and promising type has been extensively studied. In this study, a model for a PSC prepared in ambient air was established by using SCAPS-1D. After that, it was further analyzed through varying the defect density of the perovskite absorber layer (Nt), the thin film thickness and energy-level matching between the electron transport layer (ETL), the perovskite absorber layer and the hole transport layer (HTL), for a better understanding of the carrier features. The Nt varied from 1.000 × 1011 to 1.000 × 1017 cm−3. The performance of the solar cell is promoted with improved Nt. When Nt is at 1.000 × 1015 cm−3, the carrier diffusion length reaches μm, and the carrier lifetime comes to 200 nm. The thickness of the absorber layer was changed from 200 to 600 nm. It is shown that the absorber layer could be prepared thinner for reducing carrier recombination when at high Nt. The thickness effect of ETL and HTL is weakened, since Nt dominates the solar cell performance. The effect of the affinity of ETL (3.4–4.3 eV) and HTL (2.0–2.7 eV), together with three energy-level matching situations “ETL(4.2)+HTL(2.5)”, “ETL(4.0)+HTL(2.2)” and “ETL(4.0)+HTL(2.5)” on the performance of the solar cell were analyzed. It was found that the HTL with valence band 0.05 eV lower than that of the perovskite absorber layer could have a blocking effect that reduced carrier recombination. The effect of energy-level matching becomes more important with improved Nt. Energy-level matching between the ETL and perovskite absorber layer turns out counterbalance characteristic on Jsc and Voc, and the “ETL(4.0)+HTL(2.5)” case can result in solar cell with Jsc of 27.58 mA/cm2, Voc of 1.0713 V, FF of 66.02% and efficiency of 19.51%. The findings would be very useful for fabricating high-efficiency and low-cost PSC by a large-scale ambient air route.