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Inhibited nonradiative decay at all exciton densities in monolayer semiconductors
Science ( IF 44.7 ) Pub Date : 2021-07-23 , DOI: 10.1126/science.abi9193
Hyungjin Kim 1, 2 , Shiekh Zia Uddin 1, 2 , Naoki Higashitarumizu 1, 2 , Eran Rabani 2, 3, 4 , Ali Javey 1, 2
Affiliation  

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 (less than 1%), we circumvented VHS resonance and markedly suppressed 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 brightness levels.



中文翻译:

抑制单层半导体中所有激子密度的非辐射衰变

大多数光电器件在高光载流子密度下运行,其中所有半导体都遭受增强的非辐射复合。非辐射过程会按比例降低光致发光 (PL) 量子产率 (QY),这是直接决定最大器件效率的性能指标。尽管过渡金属二硫属化物 (TMDC) 单层在低激子密度下表现出接近统一的 PL QY,但范霍夫奇点 (VHS) 增强的非辐射激子 - 激子湮灭 (EEA) 在高激子密度下迅速降低了它们的 PL QY,并限制了它们在实际应用。在这里,通过施加小机械应变(小于 1%),我们绕过了 VHS 共振并显着抑制了单层 TMDC 中的 EEA,尽管存在高本征缺陷密度,但在所有激子密度下仍能获得接近统一的 PL QY。

更新日期:2021-07-23
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