A quantitative and spatially-resolved accounting of the performance-bottleneck in high efficiency, planar hybrid perovskite solar cells

Hybrid perovskites represent a potential paradigm shift for the creation of low-cost solar cells. Current power conversion efficiencies (PCEs) exceed 22%. However, despite this, record PCEs are still far from their theoretical Shockley−Queisser limit of 31%. To increase these PCE values, there is pressing need to understand, quantify and microscopically model charge recombination processes in full working devices. Here, we present a complete microscopic accounting of charge recombination processes in high efficiency (18-19% PCE) hybrid perovskite (mixed cation and methylammonium lead iodide) solar cells. We employ diffraction-limited optical measurements along with relevant kinetic modeling to establish, for the first time, local photoluminescence quantum yields, trap densities, trapping efficiencies, charge extraction efficiencies, quasi-Fermi-level splitting, and effective PCE estimates. Correlations between these spatially-resolved parameters, in turn, allow us to conclude that intrinsic electron traps in the perovskite active layers limit the performance of these state-of-the-art hybrid perovskite solar cells.