高效无镉半导体量子点发光二极管的构筑及光电性能研究

Cadmium-based quantum-dot light-emitting devices (QLEDs) have become a next-generation technology in the fields of lighting and full-color displays. However, it is challenging of the further applications of QLEDs due to the restriction of cadmium-based electronic devices and complicated fabrication process and high cost. Therefore, to develop cadmium-free QLEDs is one of the important approaches to solve the above problems. Aiming to the low efficiency and color purity of the present cadmium-free QLEDs, the research content of the proposal can be summarized as follows: 1) To study the controllable synthesis and luminescent properties of cadmium-free semiconductor QDs, and to highlight the effects of different nanostructures including the gradient distribution of the chemical composition and the shell thickness on the luminescent performance, which can enhance their colorful performance and luminescence efficiencies; 2) To develop metal oxide nanomaterials with different carrier transporting properties and to tailor their energy levels, and to realize the energy level matching, and to enhance the optoelectronic performance and device stability through the optimization of the device structure; 3) To study the fundamental physical problems of the cadmium-free QLEDs, such as the carrier injection and transport, and to build the theoretical models of carrier injection and transport, and to construct the connection of the three aspects including the nanostructures tailoring, optoelectronic performance optimizing and device physics.

含镉半导体量子点发光二极管在照明与高性能显示领域成为备受关注的下一代技术，然而由于受国际社会对含镉电子产品的限制及其制备工艺相对复杂，成本较高等方面的挑战，研制无镉半导体量子点发光二极管是解决上述问题的重要途径之一。针对目前无镉半导体量子点发光二极管发光效率和色纯度低的问题，本项目拟开展以下研究内容： 1）开展无镉半导体量子点的可控制备与发光性能研究，重点研究无镉半导体量子点的不同纳米结构如元素的梯度分布、壳层厚度等对其发光性能的影响规律，提高无镉半导体量子点的显色性能和发光效率；2）开发具有不同载流子传输特性的金属氧化物纳米材料，调控其能级结构，实现各功能层之间的能级匹配，优化器件结构，提高器件光电性能和稳定性；3）研究无镉半导体量子点发光二极管中载流子注入和输运等基本物理问题，建立载流子注入和输运理论模型，构建“材料结构调控-器件性能优化-器件物理”三者之间的内在联系。

随着国际社会对含镉电子产品的限制，无镉半导体量子点发光二极管成为国内外科学和产业界关注的焦点之一，也是下一代照明和显示技术的有力竞争者之一。本项目选用多元铜基硫族半导体纳米晶和磷化铟量子点作为研究对象，重点开展了三方面的工作：1）通过调控多元铜基硫族半导体纳米晶的结构和组分优化其发光性能，最终多元铜基硫族半导体纳米晶的光致发光量子产率可达90%；2）通过比较不同金属离子对掺杂ZnO纳米颗粒的的能级结构和电子传输速率的影响规律，发现Mg掺杂ZnO纳米颗粒作为电子传输层的量子点发光二极管的器件性能最佳，在此基础之上进行氯离子钝化降低其表面缺陷态，从而进一步提高器件性能，其最高外量子效率可达4%。在此基础之上通过空穴传输层的界面工程调控进一步提高器件综合性能，其最高外量子效率可达5.6%。3） 探讨了不同类型和不同结构的多元铜基硫族半导体纳米晶的光催化制氢性能，通过调控材料的形貌、组分、能级结构和晶面等优化了其光催化制氢性能，并通过理论计算进行了验证。项目执行期间在Adv. Opt. Mater., ACS Photonics和Opt. Express等光学类相关期刊上发表高水平学术论文24篇，其中影响因子大于4的论文17篇，授权国家发明专利1项。培养1名年轻教师晋升副教授，培养毕业博硕士研究生7人。