钙钛矿红光纳米晶的研究及其暖白光LED探索

The red light-emitting material having a narrow band can improve both color rendering index, correlated color temperature and lumen equivalent of white LEDs efficiently, which have attracted the widespread attention. However, the red-emitting light phosphors current have some problems as low efficiency, unstable characteristic, spectral mismatch and so on. This project aims to develop a new type of red fluorescent material on the basis of perovskite nanocrystals for blue light conversion WLEDs. Specifically, we try to gain a series of monodisperse perovskite nanocrystals with better stability and narrow emission by doping, temperature control, composition change, structure regulation and molecular surface modification or other means. We endeavor to clarify the relevance between the structure and the physical properties, the optical properties. In order to meet the requirement of commercial white LEDs, we also find the methods to improve the quantum efficiency and stability of the perovskite nanocrystals. This work provides the theoretical and experimental basis for the application of the red perovskite nanocrystal in white LEDs field and promotes the development of innovation of novel phosphor design concept.

具有窄带发射的红光材料在改善蓝光转换型WLED的色温、显色指数和流明效率方面效果显著,受到广泛关注。但是现阶段红光材料在改善白光LED方面存在激发效率较低、不稳定、光谱不匹配等问题。本项目围绕蓝光转换型WLED用钙钛矿红光纳米晶展开研究。通过掺杂、控制温度、改变组成、结构调控及表面功能分子修饰等手段，实现了一系列单分散钙钛矿纳米晶的可控合成和稳定窄带发射。对材料结构与物理特性、光学性质之间的关联性进行系统研究，探究使材料的荧光量子产率提高以及发光稳定性改善的途径，旨在实现材料性能与蓝光转换型WLED的要求相匹配,将钙钛矿红光纳米晶发展成一类暖白光LED可用的材料。该工作为钙钛矿红光纳米晶在白光LED领域的应用提供依据，并推动新型白光LED用红光材料设计理念的创新发展。

钙钛矿纳米晶作为一类新型的发光材料，对推动传统蓝光转换型白光LED的发展具有重要意义。本项目选择一系列无毒廉价的卤化物作为前驱体，通过阴离子交换反应，实现了一系列单分散CsPbX3 (X=Cl, Br, I)纳米晶的可控合成，实现了从紫外光区到可见光区以及近红外区的全波段光谱调控，并从卤化物键能的角度对阴离子交换反应做了系统评价。在此基础上，首次发展了一种两相阴离子交换法，成功制备一系列高效率、发光颜色可调、稳定性较好的CsPbX3纳米晶；其中，具有蓝紫光发射的CsPbCl3纳米晶的量子效率达到95%以上，卤化物作为前驱体成功实现了高浓度合成CsPbX3纳米晶。为了进一步提高钙钛矿纳米晶的稳定性，本项目将吸附了Cs+离子的二维材料如蒙脱土，高岭土等二维材料作为CsPbX3纳米晶的前驱体，在二维材料表面原位制备了从蓝光到绿光到红光的CsPbX3纳米晶，二维材料对CsPbX3纳米晶锚定效应避免了小尺寸效应导致的团聚，提高了CsPbX3纳米晶的稳定性，且材料的最大的量子效率在73%左右。最终，本项目将合成的钙钛矿纳米晶与蓝光芯片结合，制备了显色指数较好，发光效率较高的白光LED。上述工作共发表论文6篇，申请专利6项。