Kavli Affiliate: Ali Javey
| First 5 Authors: Hyungjin Kim, Shiekh Zia Uddin, Naoki Higashitarumizu, Eran Rabani, Ali Javey
| Summary:
Most optoelectronic devices operate at high photocarrier densities, where all
semiconductors suffer from enhanced nonradiative recombination. Nonradiative
processes proportionately reduce photoluminescence (PL) quantum yield (QY), a
performance metric that directly dictates the maximum device efficiency.
Although transition-metal dichalcogenide (TMDC) monolayers exhibit near-unity
PL QY at low exciton densities, nonradiative exciton-exciton annihilation (EEA)
enhanced by van-Hove singularity (VHS) rapidly degrades their PL QY at high
exciton densities and limits their utility in practical applications. Here, by
applying small mechanical strain (< 1%), we circumvent VHS resonance and
drastically suppress EEA in monolayer TMDCs, resulting in near-unity PL QY at
all exciton densities despite the presence of a high native defect density. Our
findings can enable light-emitting devices that retain high efficiency at all
brightnesses.
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