基于新型InP基核壳量子点的高效电致发光器件的构筑及其性能研究

Quantum dot light-emitting diodes (QLEDs) have recently received considerable attention for the next generation lighting and display systems due to their narrow emission linewidth, high brightness, colour tunability, and cost-effective fabrication techniques. Rapid progress has been made in the QLEDs’ performance, and now QLEDs are emerging as an undeniable competitor to organic light-emitting diodes (OLEDs). However, the intrinsic toxicity of Cd based quantum dots makes them environmentally restricted, which has thus hindered the ultimate commercialization of the QLED technology. To solve the issues of the low efficiency and short operating lifetime in current cadmium-free QLED devices, in this project, we intend to prepare highly efficient InP based quantum dots which are suitable for QLEDs through the design of new core-shell structure, material composition adjustment and surface modification. And the performances of the proposed cadmium-free QLEDs will be further improved by a series of follow-up approaches such as replacing the organic carrier transport materials with stable inorganic transport materials, improving the carrier injection and charge balance in device by interface control/doping methods and enhancing the light extraction efficiency by light outcoupling strategy. Our research will also devote to the development of all-solution processed QLEDs for reducing device fabrication cost. The research project will be a beneficial attempt towards making low-cost, high-performance, environmentally-friendly QLEDs.

量子点发光二极管（QLED）以其发射光谱窄、发光亮度高、颜色易调节、制备成本低等一系列优点，成为了下一代发光显示领域的研究热点。目前，QLED器件的性能已得到迅速提升，成为了有机LED (OLED）等显示技术的有力竞争者。然而，镉基量子点的毒性问题，已严重制约了QLED技术的商业推广。本项目针对非镉基QLED发光效率低、寿命短的现状，通过新型核壳结构的设计、调节材料组成、表面配体交换等技术手段，获得适用于QLED器件的高效InP基量子点；并采用稳定的金属氧化物代替有机半导体作为器件载流子传输层，运用界面调控/p型掺杂技术优化载流子的注入和平衡输运，通过光耦合技术改善器件光取出效率等方式探索提高QLED器件效率及稳定性的新方法与物理机制。此外，研究还致力于开发全溶液过程构筑QLED器件的加工技术，以降低器件制作成本。该项目的实施将为实现低成本高性能环保型量子点发光器件做出有益尝试。

量子点发光二极管（QLED）具有很多优越的性能，发射线宽窄，发光亮度和效率高，发光范围广，制备成本低廉等，被认为是未来新型显示领域的有力竞争者。然而，目前市场上的高效QLED（基于CdSe的QLEDs）含重金属有毒元素，在欧洲或美国已受到限制。本项目针对非镉基QLED发光效率低、寿命短的现状，在以下三个方面取得了创新成果：.A、高品质无镉量子点：通过新型的多周期核壳结构及梯度循环升温包覆策略，实现了大尺寸高品质InP基量子点的合成，荧光量子产率最高可达80%，同时发光光谱窄至40 nm，具有非常优异的发光性能，同时稳定性也得到了显著改善；同时采用Ag、Mn共掺杂的方式制备了高亮度Ag, Mn: Zn-Ga-S/ZnS白光量子点，发光效率达到了90%，量子点的稳定性也得到了改善，在高温或长时间紫外线照射下仍能保持高的荧光强度。.B、高效率高稳定QLED：采用稳定性的金属氧化物NiO代替有机半导体PEDOT:PSS作为器件载流子传输层，运用p型掺杂技术优化载流子的注入和平衡输运，所制备QLED器件的外量子效率为10.5%，通过用Cu:NiO薄膜替代PEODT:PSS材料，量子点器件的操作使用寿命被延长了几乎四倍。此外还采用铜掺杂磷钨酸代替PEDOT:PSS作为空穴注入层，实现了接近20%外量子效率的倒置QLED器件，器件寿命相比基于PEDOT:PSS的QLED寿命高5倍。.C、高效无镉QLED：在理解限制InP基QLED效率关键因素的基础上，结合倒置器件结构并设计合理的载流子传输层，将厚壳InP基量子点应用到QLED器件中，大幅度提高了InP基QLED的外量子效率（6.6%），为后续设计高效无镉QLED提供了指导。..此外，本项目还研究了多种高效长寿命QLED器件，包括全无机QLED器件，串联结构QLED器件，柔性QLED器件，以及钙钛矿发光二极管的研究。