A liquid matrix is beneficial for improving the luminescence performance of quantum dots (QDs), although it is difficult to be packaged with light-emitting diode (LED) chips. In this study, liquid-QDs with chlorobenzene solution and melamine-modified urea-formaldehyde (MUF) were used as the core and shell structures, respectively, successfully yielding liquid-QD/MUF microcapsules for white LED packaging. The concentration of the liquid-QDs in the microcapsules was optimized, demonstrating an increase of 15.9% in the luminous efficiency, as compared to the traditional solid-QDs at a specific QD energy proportion. The efficiency roll-off can be attributed to the increased reabsorption and back-scattering loss at higher liquid-QDs and microcapsules concentrations. It was also confirmed that the liquid-QD/MUF microcapsules have an excellent thermal stability below 200 °C, owing to the protection of the MUF shells. Finally, white LEDs compounding the red liquid-QD/MUF microcapsules and YAG phosphor particles were fabricated, achieving a high luminous efficiency of 149.2 lm/W at 20 mA, correlated color temperature of 3301 K, and color rendering index of 88.8. This study will open new research avenues for liquid-QD packaging in white LEDs.

中文翻译：

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用于白光发光二极管的高效液体量子点/三聚氰胺改性尿素甲醛微胶囊

尽管难以与发光二极管（LED）芯片一起封装，但是液体基体对于改善量子点（QD）的发光性能是有益的。在这项研究中，分别采用含氯苯溶液的液体量子点和三聚氰胺改性的脲醛（MUF）作为壳结构，成功地制备了用于白光LED封装的液体量子点/ MUF微胶囊。优化了微囊中液体QD的浓度，与传统的固体QD在特定QD能量比例下相比，发光效率提高了15.9％。效率下降可归因于在较高液体QD和微胶囊浓度下增加的重吸收和反向散射损失。还证实，由于对MUF壳的保护，QD / MUF液体微囊在200°C以下具有出色的热稳定性。最终，制造出将红色液体-QD / MUF微胶囊和YAG荧光粉颗粒混合在一起的白色LED，在20 mA下实现了149.2 lm / W的高发光效率，相关色温为3301 K，显色指数为88.8。这项研究将为白光LED的液体QD封装开辟新的研究途径。