ZnSe基蓝光量子点的中间壳层结构调控及其发光性能研究

摘要/Abstract

摘要： ZnSe作为一种不含重金属的宽带隙量子点(QDs),近年来在蓝光量子点及其发光二极管器件领域受到广泛关注。然而,ZnSe基核壳结构蓝光量子点的核壳界面处通常存在较大的晶格失配,易于形成缺陷态捕获载流子,从而影响其光学性能。本文通过将均质的单层ZnSeS合金层替换为具有组分渐变结构的ZnSeS合金层,合成了具有径向方向Se/S浓度渐变梯度的ZnSeS合金中间壳层的ZnSeTe/ZnSe/ZnSeS/ZnS量子点,并利用X射线衍射谱、稳态光致发光光谱、时间分辨发光光谱、透射电镜和电致发光测试等表征手段研究了不同合金中间壳层对量子点结构、形貌和光学性能的影响。结果表明,所合成的具有组分梯度ZnSeS壳层的量子点的发射波长均为深蓝色(444.5 nm),发射线宽窄(＜18 nm),尺寸均一,具有闪锌矿结构,结晶度高;随着ZnSeS合金中间壳层沿量子点径向方向组分渐变平滑度的不断提高,量子点的荧光量子效率(PLQY)和色纯度等光学性质依次改善,其中通过S原子扩散形成的具有线性缓变ZnSeS壳层的量子点具有最窄的发射线宽(15.8 nm)和最高的PLQY(20.7%)。利用这种具有最优荧光性能的量子点作为发光材料制备的发光二极管器件的最大外量子效率为1.8%,最高亮度为750 cd/m²。本研究提出的量子点合成方案和结构优化策略有助于促进高质量无毒蓝光ZnSe基核/壳量子点的发展。

关键词: 无毒蓝光量子点, 核/壳结构, 梯度合金壳, ZnSe, 量子点发光二极管, 发光性能

Abstract: As a kind of heavy-metal-free wide bandgap quantum dots (QDs), ZnSe has received extensive attention in the field of blue quantum dots and its light-emitting diodes in recent years. However, there is usually a large lattice mismatch at the core-shell interface of ZnSe based blue quantum dots, where defect states can be easily formed to capture charge carriers and thus deteriorate their optical properties. In this work, ZnSeTe/ZnSe/ZnSeS/ZnS quantum dots with Se/S graded-composition ZnSeS intermediate shells in radial direction were synthesized by replacing the homogeneous single-layer ZnSeS shell with the graded-composition ZnSeS shells. X-ray diffraction, steady-state photoluminescence spectroscopy, time-resolved luminescence spectroscopy, transmission electron microscopy and electroluminescence measurement techniques were used to study the effects of the different intermediate shells on the structure, morphology and optical properties of the synthesized quantum dots. The results show that, all of the synthesized quantum dots emit deep blue light (444.5 nm) with narrow full widths at half maximum (<18 nm), and they also have uniform size and a zinc blende structure with high crystallinity. As the smoothness of the composition gradient in the ZnSeS intermediate shell along the radial direction is continuously improved, the optical properties such as photoluminescence quantum yield (PLQY) and color purity of the quantum dots are gradually enhanced. Among them, the quantum dots with the linearly graded ZnSeS shells formed by S atom diffusion have the narrowest full width at half maxium (15.8 nm) and the highest PLQY (20.7%). The maximum external quantum efficiency and brightness of the light-emitting diode device prepared using the quantum dots with optimal fluorescence performance as emitting materials are 1.8% and 750 cd/m², respectively. The quantum dot synthesis scheme and structural optimization strategy proposed in this study may contribute to the development of high-quality non-toxic blue ZnSe based core/shell quantum dots.

Key words: non-toxic blue quantum dot, core/shell structure, gradient alloy shell, ZnSe, quantum dot light-emitting diode (QLED), optical property

中图分类号:

伍仕停, 余春燕, 方佳庆, 徐阳, 翟光美. ZnSe基蓝光量子点的中间壳层结构调控及其发光性能研究[J]. 人工晶体学报, 2024, 53(7): 1160-1169.

WU Shiting, YU Chunyan, FANG Jiaqing, XU Yang, ZHAI Guangmei. Intermediate Shell Structure Regulation and Optical Properties of ZnSe Based Blue Quantum Dots[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2024, 53(7): 1160-1169.

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