Silicon Quantum Dots for Light-Emitting Diodes Extending to the NIR-II Window,ACS Applied Nano Materials

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Silicon Quantum Dots for Light-Emitting Diodes Extending to the NIR-II Window
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2021-10-21 , DOI: 10.1021/acsanm.1c02223
Junpei Watanabe _{1,

2} , Hiroyuki Yamada _{1,

3} , Hong-Tao Sun ₁ , Taku Moronaga ₄ , Yasushi Ishii ₂ , Naoto Shirahata _{1,

2,

3}

Affiliation

Biomedical applications rely on semiconductor quantum dots (QDs) exhibiting electroluminescence (EL) properties in the wavelength range between 1.0 and 1.7 μm (called the second near-infrared window, NIR-II). However, developing heavy-metal-free QDs remains a challenge. Herein, we report, for the first time, a colloidal silicon QD light-emitting diode (Si-QLED), which exhibits an EL spectrum with a peak at 1.0 μm along with a high external quantum efficiency (EQE) value of 4.84%, which is close to the record value among reported NIR-II EL devices. SiQDs as optically active layers are synthesized by thermal disproportionation of hydrogen silsesquioxane derived from triethoxysilane, followed by hydrofluoric etching. The photoluminescence quantum yield of SiQDs is improved up to 53% by thermal hydrosilylation of 1-decene, followed by careful extraction of highly emitting QDs using size exclusion chromatography. Si-QLEDs have an inverted device architecture with multilayers, leading to stable emission properties even at a high applied voltage. Furthermore, we demonstrate a spectral shape tuning of the EL spectra by taking advantage of a large Stokes shift between the optical absorption and emission, the property inherent to QDs of indirect band gap Si crystals.

中文翻译：

用于扩展到 NIR-II 窗口的发光二极管的硅量子点

生物医学应用依赖于在 1.0 到 1.7 μm 之间的波长范围内表现出电致发光 (EL) 特性的半导体量子点 (QD)（称为第二近红外窗口，NIR-II）。然而，开发不含重金属的量子点仍然是一个挑战。在此，我们首次报道了一种胶体硅 QD 发光二极管 (Si-QLED)，其 EL 光谱在 1.0 μm 处具有峰值，并且外量子效率 (EQE) 值为 4.84%，这接近于报告的 NIR-II EL 设备的记录值。SiQDs 作为光学活性层是通过热歧化衍生自三乙氧基硅烷的氢倍半硅氧烷，然后进行氢氟蚀刻合成的。通过 1-癸烯的热氢化硅烷化，SiQDs 的光致发光量子产率提高了 53%，然后使用尺寸排阻色谱仔细提取高发射 QD。Si-QLED 具有多层倒置器件架构，即使在高施加电压下也能产生稳定的发射特性。此外，我们通过利用光吸收和发射之间的大斯托克斯位移来展示 EL 光谱的光谱形状调谐，这是间接带隙 Si 晶体 QD 固有的特性。

更新日期：2021-11-26

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