Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

Li Na Quan, Yongbiao Zhao, F. Pelayo García de Arquer, Randy Sabatini, Grant Walters, Oleksandr Voznyy, Riccardo Comin, Yiying Li, James Z. Fan, Hairen Tan, Jun Pan, Mingjian Yuan, Osman Bakr, Zhenghong Lu, Dong Ha Kim, Edward H. Sargent

Research output: Contribution to journalArticlepeer-review

262 Scopus citations

Abstract

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.
Original languageEnglish (US)
Pages (from-to)3701-3709
Number of pages9
JournalNano Letters
Volume17
Issue number6
DOIs
StatePublished - May 10 2017

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