零维钙钛矿Cs4PbBr6量子点的合成及电致发光性能研究

Quantum dot (QD) light-emitting diodes (LEDs) have the advantage of low energy consumption, and the research on QD LEDs are in line with the national strategic requirements of energy saving and emission reduction. Comparing to traditional CdSe and InP QDs, all inorganic perovskite QDs have purer emission color, higher photoluminescence (PL) quantum yields (QYs), wider range of the luminescence spectra, and easier synthetic processes. Comparing to three-dimensional perovskite CsPbBr3, the zero-dimensional perovskite Cs4PbBr6 not only has similar or even better optical properties, but also has better stability. On the basis of our previous work, this project plans to realize controllable preparation of Cs4PbBr6 QDs; reveal the luminescent mechanism of Cs4PbBr6 QDs, put forward specific proposals for improving their PL QYs; shorten or remove surface ligands of Cs4PbBr6 QDs, improve the electrical properties of QD films; design a logical device structure, achieving efficient and stable Cs4PbBr6 QD LEDs through optimizing the change injection and transportation. There are no study on electroluminescent properties of Cs4PbBr6 QDs been reported. The Cs4PbBr6 QDs that we intend to synthesize in this project are expected to improve the poor stability of perovskite materials, and make a contribution to well-performed QD display applications.

量子点发光二极管的能耗低，对它的研究符合国家节能减排的战略要求。同传统的CdSe和InP量子点相比，全无机钙钛矿量子点的发光颜色更纯，荧光量子产额更高，光谱覆盖范围更广，合成条件更加简单。同三维钙钛矿CsPbBr3相比，零维钙钛矿Cs4PbBr6不仅具有同样优异甚至更佳的光学性质，并且还具有更好的稳定性。本项目拟在我们前期工作的基础之上，实现Cs4PbBr6量子点的可控制备；揭示Cs4PbBr6量子点的发光机理，提出提高其荧光量子产额的具体方案；短化或去除Cs4PbBr6量子点的表面长碳链配体，优化其薄膜的电学性质；设计合理的器件结构，通过优化载流子的注入与传输来实现高效、稳定的Cs4PbBr6量子点发光二极管的制备。Cs4PbBr6量子点的电致发光性质未见报道。本项目拟合成的Cs4PbBr6量子点，有望提升钙钛矿材料较差的稳定性，为制备性能优异的量子点显示器件做出贡献。

本项目围绕铯铅卤素钙钛矿纳米晶展开研究，发现相较于纯相Cs4PbBr6纳米晶而言，Cs4PbBr6与CsPbBr3的混相纳米晶材料性质更优：以CsPbBr3作为发光中心、Cs4PbBr6作为分散主体的混相材料兼具良好的荧光性能与稳定性。将合适比例的Cs4PbBr6与CsPbBr3混相纳米晶用作电致发光器件的发光材料，表现出优异的性能，且具有比CsPbBr3纳米晶发光二极管更好的器件稳定性。围绕钙钛矿纳米晶发光二极管稳定性差和效率低的不足之处，在研究钙钛矿量子点生长结晶机制的基础上，通过材料合成与器件结构设计，实现了高效稳定的钙钛矿量子点发光二极管的制备，我们将CsPbBr3发光二极管的半衰期从15小时提升至250小时，将CsPbI3发光二极管的外量子效率逐步从7.25%、11.2%、11.8%、13.5% 提升至15.1%，为推动显示用发光二极管在基础研究和实际应用方面的进步做出贡献。