Precise regulation of photoluminescence properties and ligands of CdSe quantum dots based on microfluidic systems
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摘要:
本研究提出并构建了一种基于微流控技术的CdSe量子点“合成-表面配体修饰”一体化新策略，旨在实现对量子点发光性质的精准、高效调控，以满足显示、成像及光学传感等领域对量子点光学特性的特定需求。研究工作首先构建了适用于量子点材料合成的微流控平台，通过高通量精准控制多种反应条件实现高效合成，系统探究了反应温度、时间及前体配比对CdSe量子点生长过程及其发光性能的影响规律。得益于微流控合成的高效传质与传热，反应时间从传统配体修饰方法的1小时，高效缩短至5分钟。在此基础上，针对功能化配体修饰过程中量子点发光特性（如发光颜色、半峰宽等）易发生偏移的问题，本研究首次在微流控系统中引入油酸（OA）作为表面修饰配体，通过配体的高效稳定锚定，使量子点发光效率提升3倍，有效地抑制了量子点的再生长与团聚行为，显著保持了量子点发光波长和半峰宽的稳定性。本研究创新性使用的微流控技术，不仅为量子点尺寸与发光颜色的精准调控提供了可重复、可放大的平台技术，还实现了量子点发光效率与稳定性的协同优化，为量子点材料在发光显示、量子光源等领域的实际应用奠定了坚实的技术基础。
Abstract:This research reported a novel integrated strategy based on microfluidic technology for the synthesis and surface ligand modification of CdSe quantum dots (QDs). The strategy aims to achieve precise and efficient regulation of the luminescence properties of QDs to meet the specific requirements for their optical characteristics in fields such as display, imaging, and optical sensing. Firstly, a microfluidic platform suitable for QDs synthesis was developed, enabling high-throughput and precise control of multiple reaction conditions for efficient synthesis. We systematically investigated the influence of reaction temperature, time, and precursor ligand ratios on the growth process and luminescence properties of CdSe QDs. Benefiting from the efficient mass and heat transfer of the microfluidic platform, the reaction time was significantly reduced from the 1 hours required by traditional ligand modification methods to just 5 minutes in our design. To address the issue of spectral shifts in luminescence properties (such as emission color and full width at half maximum, FWHM) during functional ligand modification, this research introduced oleic acid (OA) as a surface modification ligand in the microfluidic system. Through efficient and stable anchoring of OA ligands, the luminescence efficiency of the quantum dots was enhanced by threefold, while successfully suppressing regrowth and agglomeration behaviors, thereby maintaining the stability of the emission wavelength and FWHM. The innovative use of microfluidic technology in this research not only provides a reproducible and scalable platform technology for precise regulation of QD size and luminescence color but also achieves synergistic optimization of QD luminescence efficiency and stability. Our strategy paves a technical avenue for the practical application of QDs materials in fields such as luminescent displays and quantum light sources.
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图 1 CdSe合成、配体修饰示意以及微流控反应平台系统图。
Figure 1. Synthesis process of CdSe QDs, surface modification of CdSe QDs with OA ligands and the microfluidic synthesis system.
图 2 不同反应时间下，CdSe量子点的 (a) 吸收光谱 (b)发光光谱 (c) PLQY和FWHM。 (d) 加热时间为30 s、80 s和100 s的CdSe发光寿命曲线。
Figure 2. (a) Absorption spectra, (b) PL spectra (c) PLQY and FWHM of CdSe QDs at different reaction times. (d) The PL lifetime of CdSe QDs reacted of 30 s, 80 s and 100 s.
图 3 不同反应温度下，CdSe的 (a) 吸收光谱 (b) 发光光谱以及紫外光下不同粒径Cdse发光照片。 (c) PLQY和FWHM。 (d) 反应温度230 °C、240 °C和250 °C的CdSe发光寿命曲线。
Figure 3. (a) Absorption spectra, (b) PL spectra (insert photos are CdSe with varied diameters under UV light), and (c) PLQY and FWHM of CdSe QDs at different reaction times. (d) The PL lifetime of CdSe under reaction temperature at 230 °C、240 °C and 250 °C.
图 4 CdSe量子点 (a) 吸收光谱 (b) 发光光谱 (c) PLQY和FWHM随Se:Cd的摩尔比的变化。(d) Se/Cd 前体摩尔比值为0.5、1和1.5时的CdSe发光寿命。
Figure 4. (a) Absorption spectra, (b) photoluminescence spectra, (c) peaks position of Abs and PL and (d) The PL lifetimes of CdSe at Se/Cd molar ratios of 0.5, 1 and 1.5.
图 5 配体修饰(a) 前(b) 后CdSe 545的吸收光谱、发光光谱。插图为TEM图像以及粒径统计。(c)配体修饰前后的发光寿命。(d) 不同粒径CdSe在微流控配体修饰前后的PLQY。(e) CdSe 545配体修饰前后的XRD衍射图谱。(f) ODPA和微流控配体修饰前CdSe 545的P 2p XPS图谱。配体修饰(g)前(h)后CdSe 545的在紫外LED激发下的发光光谱图。
Figure 5. Ligand modification of (a) before and (b) after CdSe 545: Absorption spectra, photoluminescence spectra, TEM images, and particle size statistics. (c) PL lifetimes, (d) PLQYs of CdSe with different particle sizes, (e) XRD diffraction patterns of CdSe 545 before and after ligand modification. (f) P2p XPS spectra of ODPA and CdSe 545 before microfluidic ligand modification. Luminescence spectra and photos of CdSe 545 under UV LED excitation (g) before and (h) after ligand modification.
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