Efficient wide-bandgap perovskite solar cells (PSCs) enable high-efficiency tandem photovoltaics when combined with crystalline silicon and other low-bandgap absorbers. However, wide-bandgap PSCs today exhibit performance far inferior to that of sub-1.6-eV bandgap PSCs due to their tendency to form a high density of deep traps. Here, we show that healing the deep traps in wide-bandgap perovskites—in effect, increasing the defect tolerance via cation engineering—enables further performance improvements in PSCs. We achieve a stabilized power conversion efficiency of 20.7% for 1.65-eV bandgap PSCs by incorporating dipolar cations, with a high open-circuit voltage of 1.22 V and a fill factor exceeding 80%. We also obtain a stabilized efficiency of 19.1% for 1.74-eV bandgap PSCs with a high open-circuit voltage of 1.25 V. From density functional theory calculations, we find that the presence and reorientation of the dipolar cation in mixed cation–halide perovskites heals the defects that introduce deep trap states.
|Original language||English (US)|
|State||Published - Aug 6 2018|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OSR-2017-CPF-3321-03
Acknowledgements: This publication is based in part on work supported by the US Office of Naval Research (Grant Award No.: N00014-17-1-2524), by an award (OSR-2017-CPF-3321-03) from the King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellence Program, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. The work of H.T. was also supported by a Rubicon grant (680-50-1511) from the Netherlands Organization for Scientific Research (NWO) and by the Thousand Talent Program for Young Outstanding Scientists in China. D.B. and M.A. acknowledge the support by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, and Materials Sciences and Engineering Division, under Contract No. DE-AC02-05-CH11231. Materials Project program KC23MP. M.I.S. acknowledges the Government of Canada’s Banting Postdoctoral Fellowship Program for financial support. The DFT simulation is supported by the IBM Canada Research and Development Center through the Southern Ontario Smart Computing Innovation Platform (SOSCIP). A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.