碳量子点发光二极管电致发光效率及调色机制研究

Carbon quantum dots (CDs) is a kind of nano material with excellent fluorescence properties. Because of carbon quantum dots light stability, light tuning, high fluorescence quantum efficiency, good biocompatibility, resistance to photo-bleaching, raw materials widely, and simple preparation, CDs can compete with semiconducting quantum dot CdSe/ZnS made up of core-shell structures. It's been proven that CDs can be used to make carbon quantum dot light-emitting diode (CLEDs). But for now, to find a simple, independent, low consumption, without passivation, and environment friendly method of large-scale preparation of efficient fluorescent CDs has been a huge challenge yet. This project intends to explore the best method of fabricating highly fluorescent CDs, and luminescent mechanism and controllable preparation technology of emit red, green, blue and white fluorescent CDs; to reveal electroluminescent and color/wavelength regulation mechanism of CLEDs, and to look for optimum device structure and simple color tuning method of high brightness white CLEDs by optimizing device structures and material combinations, and selecting CD sizes, doping types and passivation methods. The research results of this project can promote high efficiency, high stability, high brightness of white CLEDs widely used in the field of thin film display devices, green lighting, biological imaging, etc.

碳量子点（CDs）是一种具有优异荧光特性的纳米材料。CDs具有可调谐荧光和抗光漂白的特点。它已被证明可用于制作碳量子点发光二极管（CLEDs）。由于CDs发光稳定，生物相容性好，无毒，原料广泛，制备简易，成本低廉，它可与核壳结构的半导体量子点CdSe/ZnS竞争，用于显示和固体照明。但目前要寻找一种简单、低消耗、无需钝化而又环境友好的方法大规模制备高效荧光CDs仍是一项巨大的挑战。本项目拟以高效荧光CDs和CLEDs制备为先导，研究CDs荧光增强的有效方法，以及可发射红、绿、蓝荧光甚至直接发射白色荧光的CDs发光机理和量子效率；揭示CLEDs电致发光及其调色机制，通过CDs尺寸、掺杂种类和钝化方式的选择，以及器件结构和材料组合的优化，寻找能实现高亮度白光CLEDs的最优器件结构和简易调色方法。本项目研究可促进高效率、高稳定性、高亮度的CLEDs 在薄膜显示、绿色照明、生物成像等领域的应用。

本项目以红绿蓝三基色荧光碳量子点（CQDs）制备为先导，系统地研究了碳量子点发光二极管（CLEDs）的器件原理和制作方法、高亮度CLEDs的发光机制以及白光CLEDs器件的最优结构，并以红、绿、蓝三基色碳量子点混合作为发光层，实现了高亮度白光CLEDs器件。然后，采用高荧光量子产率的碳量子点作为发光层来提高CLEDs的发光效率。我们还研究了CQDs荧光增强的有效方法，以及可发射红、绿、蓝荧光CQDs的发光机理；揭示了CLEDs电致发光及其调色机制。通过CQDs尺寸、掺杂种类和钝化方式的选择，以及器件结构和材料组合的优化，找到了高亮度白光CLED s的最优器件结构和简易调色方法。本项目组用自制的CQDs作发光材料制备出电致发光和光致发光的CLEDs器件，其亮度已达到1150-1160 cd/m2，最高达1800 cd/m2。此研究结果可为CLEDs在薄膜显示、绿色照明、生物成像等领域的应用提供参考数据和技术支持。