Efficiency Roll-Off Free Electroluminescence from Monolayer WSe2,Nano Letters

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Efficiency Roll-Off Free Electroluminescence from Monolayer WSe2
Nano Letters ( IF 9.6 ) Pub Date : 2022-06-21 , DOI: 10.1021/acs.nanolett.2c01311
Shiekh Zia Uddin _{1,

2} , Naoki Higashitarumizu _{1,

2} , Hyungjin Kim _{1,

2} , I K M Reaz Rahman _{1,

2} , Ali Javey _{1,

2}

Affiliation

Exciton–exciton annihilation (EEA) is a nonradiative process commonly observed in excitonic materials at high exciton densities. Like Auger recombination, EEA degrades luminescence efficiency at high exciton densities and causes efficiency roll-off in light-emitting devices. Near-unity photoluminescence quantum yield has been demonstrated in transition metal dichalcogenides (TMDCs) at all exciton densities with optimal band structure modification mediated by strain. Although the recombination pathways in TMDCs are well understood, the practical application of light-emitting devices has been challenging. Here, we demonstrate a roll-off free electroluminescence (EL) device composed of TMDC monolayers tunable by strain. We show a 2 orders of magnitude EL enhancement from the WSe₂ monolayer by applying a small strain of 0.5%. We attain an internal quantum efficiency of 8% at all injection rates. Finally, we demonstrate transient EL turn-on voltages as small as the band gap. Our approach will contribute to practical applications of roll-off free optoelectronic devices based on excitonic materials.

中文翻译：

单层 WSe2 的效率滚降自由电致发光

激子-激子湮灭 (EEA) 是一种非辐射过程，通常在高激子密度的激子材料中观察到。与俄歇复合一样，EEA 会降低高激子密度下的发光效率，并导致发光器件的效率下降。已在所有激子密度下的过渡金属二硫属化物 (TMDC) 中证明了近统一的光致发光量子产率，并具有由应变介导的最佳能带结构修饰。尽管 TMDC 中的重组途径已广为人知，但发光器件的实际应用一直具有挑战性。在这里，我们展示了一种由可通过应变调节的 TMDC 单层组成的无滚降电致发光 (EL) 器件。我们展示了 WSe _{2的 2 个数量级的 EL 增强}通过施加 0.5% 的小应变实现单层。我们在所有注入速率下都获得了 8% 的内部量子效率。最后，我们展示了与带隙一样小的瞬态 EL 开启电压。我们的方法将有助于基于激子材料的无滚降光电器件的实际应用。

更新日期：2022-06-21

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