Abstract
We report charge recombination rates in lead iodide perovskites with alloys of formamidinium (FA) and methylammonium (MA) cations, FAxMA1-xPbI3, 0 ≤ x ≤ 0.9, prepared through ion exchange with minimal differences in morphology and charge trap density. Our results show that the trap-mediated recombination rate increases over 2 orders of magnitude with decreasing MA content. These results are consistent with a proposed mechanism that MA molecules are more effective in screening charged defects. In contrast, band-to-band charge recombination rates are minimized at an intermediate alloy composition. These findings reveal that the monovalent cations impact recombination processes through different mechanisms.
Original language | English |
---|---|
Pages (from-to) | 1298-1304 |
Number of pages | 7 |
Journal | ACS Applied Energy Materials |
Volume | 3 |
Issue number | 2 |
DOIs | |
State | Published - Feb 24 2020 |
Funding
J.J.C. and S.-H.L. acknowledge support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0016144. The work at Oak Ridge National Laboratory (ORNL) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (Y.-Z.M.) and the U.S. Department of Energy Office of Science Graduate Student Research program (B.J.F).
Keywords
- alloys
- charge carrier recombination
- ion exchange
- perovskites
- renewable energy materials
- ultrafast spectroscopy