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.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OCRF-2014-CRG3-2268
Acknowledgements: This work was supported by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy under award DE-SC0014334. PVK additionally acknowledge support from the Division of Chemical Sciences, Geosciences, and Biosciences under award DE-FC02-04ER15533, Office of Basic Energy Sciences, U.S. Department of Energy. We also thank the Notre Dame Radiation Laboratory (NDRL) for use of its facilities. The NDRL is supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences under Award Number DE-FC02- 04ER15533. JAC was supported by the Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Solar Energy Technologies Office administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE under DOE contract number DE-SC00014664. We thank Bobby To for assistance with SEM imaging and Sanjini Nanayakkara for assistance with AFM imaging. JM and AM acknowledge support of King Abdullah University of Science and Technology (KAUST) through the Award OCRF-2014-CRG3-2268. JML acknowledges support from the hybrid perovskite solar cell program of the National Center for Photovoltaics funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office under Contract No. DEAC36- 08-GO28308. All opinions expressed in this paper are the authors' and do not necessarily reflect the policies and views of DOE, ORAU, or ORISE.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.