Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission
- 주제(키워드) energy transfer , Light-emitting diodes , Monte Carlo , Perovskites , photoluminescence quantum yield , Quasi-2D perovskites
- 등재 SCIE, SCOPUS
- 발행기관 American Chemical Society
- 발행년도 2017
- URI http://www.dcollection.net/handler/ewha/000000146923
- 본문언어 영어
- Published As http://dx.doi.org/10.1021/acs.nanolett.7b00976
초록/요약
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/cm2, yielding a ratio of quantum yield to excitation intensity of 0.3 cm2/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/m2. © 2017 American Chemical Society.
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