期刊
NANO LETTERS
卷 17, 期 6, 页码 3701-3709出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b00976
关键词
Perovskites; Quasi-2D perovskites; Light-emitting diodes; Photoluminescence quantum yield; energy transfer; Monte Carlo
类别
资金
- King Abdullah University of Science and Technology (KAUST) [KUS-11-009-21]
- Ontario Research Fund Research Excellence Program
- Natural Sciences and Engineering Research Council (NSERC) of Canada
- National Research Foundation of Korea - Korean Government [2014R1A2A1A09005656, 2015M1A2A2058365]
- Connaught fund
Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm(2), yielding a ratio of quantum yield to excitation intensity of 0.3 cm(2)/mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m(2).
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