Mobile Ion Concentration Measurement and Open-Access Band Diagram Simulation Platform for Halide Perovskite Solar Cells

We propose two approaches to compute the band diagram of highly efficient perovskite solar cells, both based on the migration of a single-mobile ion (halide vacancies). The first is a full analytical approach to quickly calculate the main features of the perovskite band diagram and easily extract the mobile vacancy concentration from experimental data. The second approach is an online-open-access platform that can be used by anyone to accurately simulate their own band diagram We combine the first approach with current transient measurements to extract the mobile ion concentration for six different perovskite compositions-including perovskite solar cells with power conversion efficiencies exceeding 19%. For the devices measured herein, we obtain ion concentrations in the range 7 x 10(16)-5 x 10(17) cm(-3). We use the second approach to quantitatively discuss the implications of the mobile ion concentrations we measured in terms of device performance and stability.