具有双极传输特性的钙钛矿量子点及其高效率发光二极管

Organice-inorganic hybrid perovskite solar cells have attracted a lot of attention on itself due to the high photoelectric conversion efficiency of Organic-inorganic hybrid perovskite. Contemporaneously, attentions also been put on Organic-inorganic hybrid perovskite quantum dots(QDs) based light-emitting diodes (LEDs) , accounting for high fluorescence quantum efficiency and simple preparation process of organice-inorganic hybrid perovskite. However, there is a contradiction in the application of quantum dot devices: (1) stable and high fluorescence quantum efficiency quantum dots need to be coated with a long-chain ligand; (2) the insulating properties of long-chain ligands lead to poor carrier transfer in quantum dots films, limiting performance of relative LED devices. Different from the traditional "eclectic" treatment of this contradiction, we recently used conjugated amine ligands to solve the contradiction between "stability" and "conductivity" of quantum dots. However, how to develop stable, high fluorescence quantum efficiency perovskite quantum dots with electron and hole bipolar transport property is one of the keys to high-performance LEDs.This project will focus on the effect of organic ligands on the kinetics and stability of quantum dots of perovskite and the effect of fluorescence quantum efficiency. With development of a series of quantum dots with bipolar transmission characteristics, we can enables carrier-balanced transmission and effective radiation recombination in their LEDs. Finally, through the interface modification to avoid exciton annihilation and other effects, high-performance perovskite quantum dot light-emitting diodes could been achieved.

有机无机复合钙钛矿太阳能电池由于高光电转化效率成为国际焦点，同时此类钙钛矿材料的量子点及其发光二极管（LED）因超高的荧光量子效率和简易可靠的制备过程而备受瞩目。然而量子点器件应用存在一个矛盾：（1）稳定且高荧光量子效率量子点外侧需要包覆一层长链小分子配体；（2）长链小分子配体的绝缘特性导致量子点间差的载流子传输从而限制了其LED器件性能的提升。不同于传统 “折中”处理这个矛盾的方式，申请者近期采用共轭胺基配体解决了量子点“稳定性”与“导电性”的矛盾。然而如何发展具有电子、空穴及双极性传输且稳定、高荧光量子效率的钙钛矿量子点是其高性能LED的关键之一。本项目研究和揭示共轭烯胺的有机配体对钙钛矿量子点形成动力学及稳定性、荧光量子效率影响的规律，发展系列具有双极传输特性的量子点,实现其LED中载流子平衡传输以及有效辐射复合，并通过界面修饰避免激子猝灭等效应,最终实现高效钙钛矿量子点发光二极管。

近年来，钙钛矿量子点具有荧光量子产率高、简易便捷的合成方法等特点，在发光二极管领域展现出明显优势。然而，无论在何种钙钛矿量子点的制备过程中，烷基链配体必不可少。这些配体的绝缘性限制了载流子在量子点之间的传输，导致最终量子点器件性能低劣。.为了提高钙钛矿量子点发光二极管器件性能，我们主要通过合成制备具有双极传输特性的量子点,实现在发光二极管中载流子平衡注入与传输以及辐射复合，构建与量子点能级匹配的电子、空穴传输功能层并通过界面修饰避免激子猝灭等效应,最终实现高效钙钛矿量子点发光二极管。较好地完成了项目要求。重要的成果具体如下：.1）采用具有双端配位基团的溴胺盐1,8-正辛胺二溴（BOABr2）对室温合成的CsPbBr3进行原位钝化，以减少量子点表面溴空位的存在，其PLQY高达98%；基于BDABr2钝化的量子点制备的LED器件表现出最大发光亮度14021 Cd m-2，最大电流效率25.5 cd A-1的优异器件性能（Nano Energy 2020, 70, 104467）。.2）发展了一种两性离子表面活性剂即N,N-二甲基-N-(3-磺丙基)-1-十八烷铵内盐作为配体可以得到PLQY超过90%的甲脒铯铅溴量子点。将这种超纯绿的、高质量的量子点引入到背光显示中，Rec.2020色域覆盖度为85.7%。这也是迄今为止“最绿色”的背光。（ACS Appl. Mater. Interfaces 2020, 12, 2835−2841）。.3）采用全无机策略及IPI级联式电子传输层，有效抑制离子迁移，制备了同期国际上最稳定的绿光PeLEDs器件，并且该器件兼顾高亮度（156155 cd/m2）与高效率（EQE~11.05%）（Adv. Funct. Mater. 2020, 30, 2001834）。.4）以苯丙稀胺（3-phenyl-2-propen-1-amine，PPA）为主配体，通过DDAB及ZnBr2协同钝化配体的后处理，获得了具有高荧光量子效率的MaPbBr3钙钛矿量子点（ACS Appl. Mater. Interfaces 2022, 14, 8, 10508–10516）。.以上研究成果对于进一步实现高效钙钛矿量子点发光二极管以及推进其商业化进程有重要的实验和理论指导意义。课题发表与项目有关的高水平SCI论文15篇，授权中国发明专利1项。