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科研进展丨叶志镇院士团队在材料学顶级期刊《InfoMat》上发表重大科研成果:双基质包覆策略实现显示用高稳定性钙钛矿量子点

来源:本站   发布时间:2023年03月21日

液晶显示(LCD)是目前广泛应用的显示技术,然而常用的 LCD背光荧光粉的宽光谱特点限制了其色彩显示能力和总流明效率的进一步提升。量子点具有窄发射光谱和高荧光效率等优势,为提高LCD色彩品质和感知亮度提供了新技术路线。

铅卤钙钛矿(以下简称钙钛矿)量子点具有高的光致发光量子产率、窄的发光半峰宽、可连续调谐的带隙等优异的光学特性,是下一代发光显示材料的最佳候选者之一。然而,由于钙钛矿在高湿度、高温度和强光照射环境下容易发生离子迁移、相变和分解,这极大地影响了它们的实际应用。因此,可控制备具有高稳定性的钙钛矿量子点材料对推动其在显示领域的应用具有重要意义。

针对这一难题,我院院长叶志镇院士及其团队成员何海平教授,戴兴良研究员,樊超博士后等提出了双基质包覆策略来全面提升全无机钙钛矿量子点在高湿度、高温度、强蓝光照射条件下的稳定性,并实现钙钛矿量子点液晶显示应用。研究成果发表于材料学顶级期刊《InfoMat》(影响因子25),樊超博士后为论文第一作者,戴兴良研究员、何海平教授、叶志镇院士为论文通讯作者。

该研究工作提出一种双基质包覆策略,用Cs4PbBr6基质包覆CsPbBr3量子点,这些CsPbBr3@Cs4PbBr6核壳结构被封装在氧化硅基质中。由于良好的晶格匹配,Cs4PbBr6基质可以有效钝化CsPbBr3的表面,而氧化硅基质又进一步隔绝了CsPbBr3@Cs4PbBr6核壳结构与外界环境。通过双基质包覆获得的CsPbBr3@Cs4PbBr6/氧化硅复合材料同时具备对CsPbBr3量子点表面钝化和封装的作用,这将会极大提升钙钛矿在高温高湿和蓝光照射环境中的稳定性。

得益于双基质包覆,CsPbBr3量子点具有高于90%的荧光量子产率(PLQY),并且具有优异的光稳定性、热稳定性、水稳定性:在350 mW/cm2的强蓝光照射36小时发光无衰减;加热到180℃后可以恢复93%的发光强度;在水中浸泡100天无发光强度衰减。用双基质包覆量子点制备的扩散板在85%湿度、85℃、350 mW/cm2的强蓝光照射的综合测试条件中老化1000小时后依然能保持初始发光强度的80%以上。此外,作为合作单位的温州锌芯钛晶科技有限公司将这些钙钛矿量子应用于LCD背光组件当中,实现了131% NTSC的高色域液晶显示器。该工作提出的双基质包覆策略对设计和实现高稳定性钙钛矿材料具有重要的指导作用,并为钙钛矿液晶显示技术提供了材料基础。

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图文速递

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Figure 1. Schematic of the syntheses of the CsPbBr3@Cs4PbBr6/MS composites. Inset: phase diagram of the CsBr–PbBr2 binary system. CsPbBr3@Cs4PbBr6 nanocomposites were in situ grown in the MCM-41 MS by heating the mixed CsBr, PbBr2, and MCM-41 MS powders.

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Figure 2. Structural and optical characterisations. (A) PXRD patterns, (B) absorption and PL spectra, (C) PLQY and PL peaks, and (D) PL decay profiles of the samples obtained using different CsBr/PbBr2 values. (E) TEM image of the original MCM-41 MS, demonstrating the mesoporous structure of MCM-41 MS. Scale bar: 30 nm. The green dotted line represents the border of MS. (F) TEM image of the CsPbBr3@Cs4PbBr6/MS composites. Scale bar: 20 nm. The green dotted line indicates the border of MS. (G) High-resolution TEM image of the CsPbBr3@Cs4PbBr6 structure in MS. Scale bar: 3 nm.

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Figure 3. Moisture, thermal, and photo stability characterisations. Relative PL intensity curves of the (A) CsPbBr3@Cs4PbBr6/MS and (B) CsPbBr3/MS composites dispersed in water for 100 days. (C) Relative PL intensity curves of the CsPbBr3 QD film exposed to a high-humidity atmosphere (relative humidity: 90%) for 20 h. Pseudo-colour maps of the time-dependent PL spectra of the (D) CsPbBr3@Cs4PbBr6/MS composites, (F) CsPbBr3/MS composites, and (H) CsPbBr3 QD film subjected to blue light irradiation for 36 h. Relative PL intensity curves of the (E) CsPbBr3@Cs4PbBr6/MS composites, (G) CsPbBr3/MS composites, and (I) CsPbBr3 QD film exposed to blue light irradiation for 36 h. Pseudo-colour maps of the temperature-dependent PL spectra of the (J) CsPbBr3@Cs4PbBr6/MS composites, (L) CsPbBr3/MS composites, and (N) CsPbBr3 QD film subjected to a heating–cooling cycle. Relative PL intensity curves of the (K) CsPbBr3@Cs4PbBr6/MS composites, (M) CsPbBr3/MS composites, and (O) CsPbBr3 QD film exposed to a heating–cooling cycle.

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Figure 4. CsPbBr3@Cs4PbBr6/MS composite-based diffusion plate for LCD backlight. (A) Optical image and (B) PL spectrum of the diffusion plate. (C) Relative PL intensity curves of the CsPbBr3@Cs4PbBr6/MS composite- and CsPbBr3/MS composite-based diffusion plates subjected to the harsh commercial ageing conditions (high relative humidity of 85%, high temperature of 85 °C, and blue light irradiation with a high power density of 350 mW cm-2) for 1000 h. (D) Schematic of LCD construction. (E) Emission spectra of the perovskite-based LCD (Pe-LCD) and ordinary LCD with commercial phosphors. (F) Colour gamut coverage of the Pe-LCD. Pictures on the Pe-LCD (G) and ordinary LCD (H).

原文链接:

https://onlinelibrary.wiley.com/doi/10.1002/inf2.12417    


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