Silicon Quantum Dots for Light-Emitting Diodes Extending to the NIR-II Window
Silicon Quantum Dots for Light-Emitting Diodes Extending to the NIR-II Window
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DOI：
10.1021/acsanm.1c02223
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发表时间：
2021-10
影响因子：
5.9
通讯作者：
J. Watanabe;Hiroyuki Yamada;Hong-Tao Sun;T. Moronaga;Y. Ishii;N. Shirahata
中科院分区：
文献类型：
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作者：
J. Watanabe;Hiroyuki Yamada;Hong-Tao Sun;T. Moronaga;Y. Ishii;N. Shirahata
生物医学应用依赖于半导体量子点（QD）在1.0和1.7 μm之间的波长范围内表现出电致发光（EL）特性（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量子点发光二极管（Si-QLED），其EL光谱在1.0 μm处有一个峰值，同时沿着有一个高达4.84%的外量子效率（EQE）值，接近于已报道的近红外-Ⅱ型EL器件的最高值。作为光学活性层的硅量子点是通过由三乙氧基硅烷衍生的氢硅倍半氧烷的热分解，然后通过氢氟酸蚀刻来合成的。通过1-癸烯的热氢化硅烷化，然后使用尺寸排阻色谱法仔细提取高发射量子点，SiQD的光致发光量子产率提高到53%。Si-QLED具有多层的倒置器件架构，即使在高施加电压下也具有稳定的发射特性。此外，我们证明了一个光谱形状调谐的EL光谱利用一个大的斯托克斯位移之间的光学吸收和发射，间接带隙硅晶体的量子点固有的属性。
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.