电场作用下准二维铅卤钙钛矿离子迁移机理研究

Lead-halide Perovskite light-emitting diodes (PeLEDs) have obtained great improvement in the past several years, but the operating lifetimes are far from commercial application. One important factor that results in the instability of PeLEDs is the ion migration under electric field. Introducing quasi-two-dimensional perovskite materials into PeLEDs can improve the device lifespan. However, the mechanism of ion migration in quasi-two-dimensional perovskites is still unclear. Therefore, it is impossible to further guide the design of electric field resistant perovskite materials. This project will take the ion migration mechanism under the electric field of quasi-two-dimensional perovskites as the research object，targeting the preparation of high-efficiency, electric field resistant PeLEDs. Firstly, the evolution of optoelectronic properties of quasi-two-dimensional perovskites under electric field is studied, developing the ion migration model. Secondly, according to the ion migration model, the quasi-two-dimensional perovskite materials with electric field resistance is further designed. Finally, combined with the designed perovskites and suitable device structure, we are aiming to fabricate the electric field stable and high-efficiency PeLEDs. This project not only guides the design of high performance PeLEDs, but also helpful for the development of the perovskite solar cells.

铅卤钙钛矿发光器件发展迅速，然而器件的稳定性还存在较大问题。电场作用下的离子迁移是导致铅卤钙钛矿发光器件不稳定的重要因素。采用准二维铅卤钙钛矿可以明显提高器件的稳定性，但是目前还没有关于准二维铅卤钙钛矿离子迁移机理的研究，无法指导准二维铅卤钙钛矿材料设计。本项目拟围绕电场作用下准二维铅卤钙钛矿离子迁移机理这一关键科学问题，以制备高效率、耐电场钙钛矿发光器件为目标，研究准二维铅卤钙钛矿材料在电场作用下的光电性质演变规律，建立准二维铅卤钙钛矿离子迁移模型以及离子迁移抑制机制；根据得到的离子迁移模型，综合考虑材料的光电性质，设计耐电场的准二维铅卤钙钛矿材料；结合器件结构调控，制备耐电场、高效率的钙钛矿发光器件。本项目的开展有利于指导开发高性能的钙钛矿发光器件，对钙钛矿太阳能电池的发展也具有很好的推动作用。

金属卤化物钙钛矿材料可通过低温溶液工艺制备，是一种直接带隙半导体材料，具有高荧光量子效率、高色纯度和可调节的发光波长等优势。然而，由于其典型的离子晶体结构，当钙钛矿器件受到电场作用时，其中的离子会发生迁移现象，从而影响器件的稳定性。因此，研究离子在电场下的迁移机理对于获得稳定的钙钛矿光电器件至关重要。本项目旨在通过钙钛矿材料在电场作用下的光物理性质演变过程研究离子迁移的产生原因和抑制方法，进而制备高效率且耐电场的钙钛矿发光器件。申请人从钙钛矿发光器件中所存在的积极老化现象入手，结合原位光物理性质和界面特性表征，发现这一现象与钙钛矿材料在电场作用下产生的离子迁移相关。基于此，申请人提出了一种采用离子液体改性钙钛矿材料的界面，可在抑制离子迁移和消除积极老化现象的同时提升器件效率。此外，金属卤化物材料的化学特性使得所制备的电致发光器件中存在界面化学反应。申请人结合钙钛矿材料与相邻层所存在的界面化学研究，分析了界面化学反应对器件发光机理和性能的影响。上述工作为制备高效率、低成本的钙钛矿发光器件提供了解决方案。