Origin of open-circuit voltage reduction in high-mobility perovskite solar cells

Despite the rapid progress made in solar cell researches based on organic-inorganic hybrid perovskites, a fundamental understanding of their operation principles is still limited. This problem is associated with a lack of parameterization and modeling tools that capture complete cell behaviors. This article provides a new insight into the charge-carrier mobility in perovskite solar cells using experimentally calibrated numerical simulations. Although increasing the mobility substantially improves the short-circuit current, a simultaneous decrease in the open-circuit voltage is observed, eventually inducing efficiency roll-off in the high-mobility regime. The increased bending of potential profiles (electrode regions) and decreased electric field (central region) due to carrier diffusion were found to be the key mechanisms behind this behavior, thus providing a theoretical guideline for material and device engineering with the goal of optimum cell performance.