光谱学与光谱分析, 2020, 40 (4): 1113, 网络出版: 2020-07-02  

高色域量子点LED及其在背光显示中的应用研究

High Color Gamut Quantum Dots LED and Its Application Research in Backlight Display
作者单位
华南师范大学光电子材料与技术研究所, 广东 广州 510631
摘要
量子点因其独特优异的光学特性而被广泛应用于发光领域, 其中最突出的特点是光谱调谐方便, 只需要改变材料的尺寸, 就可实现发光光谱的调谐。 结合实际应用的需要, 选取CdSe材料作为主要研究对象, 通过改进工艺, 采用希莱克技术隔绝水氧, 使用高温热注入法, 调整原料中镉源和锌源, 硒源和硫源的比例, 获得了尺寸分别约为6.0和4.2 nm, 发光峰分别为625和525 nm, 半高宽分别为30和28 nm, 荧光量子产率分别达到82%和61%的粒径均一、 色纯度高且高效稳定核壳结构CdSe/ZnS红光和绿光量子点材料。 然后对量子点LED在背光显示中的应用进行了研究, 采用合成的红光和绿光量子点材料替代传统工艺中的荧光粉材料, 通过改进封装方式, 对量子点光转换层采用双层环氧树脂AB胶保护, 同时引入PMMA透镜包覆, 从根本上隔绝水氧。 最终得到的量子点白光LED, 红绿蓝光发射峰分别为630, 535和453 nm, 半高宽别为20, 28和30 nm, 三段光谱发射峰两侧对称性良好, 有效解决了传统荧光粉白光LED在红色光谱波段缺失的问题, 并同时实现了单色性好、 色纯度高、 色彩饱和度高等优点。 在LED积分球光色电测试系统中20 mA电流条件下测试, 得到了CIE色坐标为(0.329, 0.324)的白光量子点LED, 这是非常接近标准白光的色坐标。 其色温为5 094 K, 光效达到94.72 lm·W-1, 显色指数Ra可达78.6, 寿命超过400 h。 最后对量子点LED灯条进行封装得到背光源, 根据测试获取的白光量子点LED发射光谱, 可以得到sRGB颜色三角形, 即色域, 通过对比NTSC1931标准色域, 得到了色域覆盖率可以达到109.7%的高色域量子点LED背光源。 开发的LED背光由240个白光量子点LED制成, 并且首次成功演示了29英寸液晶电视面板, 这一结果将进一步开发量身定制的量子点, 特别是在高性能显示器应用领域。
Abstract
Quantum dots are widely used in the field of luminescence because of their unique and excellent optical properties. The most prominent feature is that the spectral tuning is convenient, and only the size of the material needs to be changed to realize the tuning of the luminescence spectrum. In combination with the needs of practical applications, CdSe materials were selected as the main research object. By improving the process, introducing Schlenk line to isolate water and oxygen, using high temperature thermal injection method, adjusting the ratio of cadmium source and zinc source, selenium source and sulfur source in raw materials, the core-shell structure CdSe/ZnS red and green quantum dot materials with high color purity and high efficiency and stability were obtained. The synthetic quantum dots have a size of about 6.0 and 4.2 nm, luminescence peaks of 625 nm and 525 nm, the full width at half maximum (FWHM) in PL spectra of 30 and 28 nm, and photoluminescence quantum yield (PLQY) of 82% and 61%, respectively. And then the application of quantum dot LED in backlight display was studied. The composite red and green quantum dot materials were used to replace the phosphor materials in the traditional process. By improving the packaging method, the quantum dot light conversion layer was protected by a double-layer epoxy resin AB glue, at the same time, a PMMA lens coating was introduced to fundamentally isolate water and oxygen. Finally, the packed quantum dot white light-emitting diodes(wLEDs) have red, green and blue emission peaks of 630, 535 and 453 nm, respectively. The FWHM of PL spectra are 20, 28 and 30 nm. The three-segment spectral emission peaks have good symmetry on both sides, effectively solving the problem that the LED is missing in the red spectral band of the traditional phosphorwLEDs. And it achieves the advantages of good monochromaticity, high color purity, and high color saturation. The quantum dot wLEDs with CIE color coordinate (0.329, 0.324) was obtained under the condition of 20 mA current in the LED integrating sphere photochromic test system. The color coordinate was very closed to the standard white light. Its color temperature was 5 094 K, the luminous efficiency reached 94.72 lm·w-1, and the color rendering index Ra could approach 78.6, and the lifetime was more than 400 h. Finally, the quantum dot LED strip was packaged to complete the backlight. According to the quantum dot wLEDs emission spectrum gained from the test, we could obtain the sRGB color triangle, ie the color gamut. By comparing the NTSC1931 standard color gamut, we discovered a high color gamut quantum dot LED backlight with a colorgamut coverage of 109.7%. The LED backlight developed was made up of 240 quantum dot wLEDs and successfully demonstrated the 29-inch LCD TV panel for the first time. This result will further develop tailor-made quantum dots, especially in high-performance display applications.

王果, 杨欣, 李东颖, 孙新雨, 方一旭, 章勇, 宿世臣. 高色域量子点LED及其在背光显示中的应用研究[J]. 光谱学与光谱分析, 2020, 40(4): 1113. WANG Guo, YANG Xin, LI Dong-ying, SUN Xin-yu, FANG Yi-xu, ZHANG Yong, SU Shi-chen. High Color Gamut Quantum Dots LED and Its Application Research in Backlight Display[J]. Spectroscopy and Spectral Analysis, 2020, 40(4): 1113.

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