无铅Sn基钙钛矿材料的缺陷调控及其电致发光器件的研究

Perovskites, especially Pb-based halide perovskites, has great application prospect in luminescent display field due to high luminous efficiency, excellent carrier transport and other optoelectronic characteristics. However, the toxicity of Pb and its environmental pollution seriously limit its industrial application. Therefore, the development of lead-free perovskite materials and devices has become a research hotspot in the field. Sn is non-toxic with similar electronic structure to Pb, thus Sn-based perovskite is expected to be an excellent candidate for lead-free perovskite. However, its defect states (valence transition, vacancy) seriously disturb the electronic structure, resulting in low luminous efficiency and poor stability.. This project aims to build Sn-based perovskite luminescent materials and luminescent devices with high efficiency and stability, and studies the dependence of luminescent performance and structural stability on components by regulating reaction conditions and changing components. By introducing oxidation/reduction inhibitors, ligands and other strategies to regulate defect types and states, and study the dynamic mechanism of carrier transition and exciton recombination. Based on the characteristics of exciton recombination, the structure optimization and interface engineering regulation are used to construct efficient and stable Sn perovskite LEDs. The project is expected to achieve efficient and stable Sn-based perovskite LEDs, reveal the physical essence of composition and ligand on structure and luminescence regulation. It is also expected to deepen the understanding of electronic structure of Sn-based perovskite, and promote the application process.

钙钛矿，尤其是Pb基卤化物体系，因其高发光效率、优异载流子输运等光电特性，在发光显示领域具有极大应用前景。然而，Pb的毒性及对环境污染等问题严重限制了产业化应用。因此，开发无铅钙钛矿材料及器件已成为领域的研究热点。Sn与Pb电子结构相似、无毒，Sn基钙钛矿有望成为无铅钙钛矿的极佳候选。但其缺陷态（价态转变、空位）严重扰乱了电子结构，致使发光效率低、稳定性差。.本项目以构筑高效稳定的Sn基钙钛矿发光材料与发光器件为目标，拟通过调控反应条件、改变组分，研究发光性能和结构稳定对组分等的依赖关系；通过引入氧化/还原抑制剂、配体等调控缺陷种类与状态，研究载流子跃迁和激子复合等动力学机制；基于激子复合特性，通过结构优化、界面工程调控，构筑高效稳定Sn钙钛矿LEDs。该项目有望实现高效稳定Sn基钙钛矿LEDs，揭示出组分、配体等对结构、发光调控的物理本质，深化Sn基钙钛矿电子结构认识，推进应用进程。

本研究以构筑高效稳定的Sn基钙钛矿发光材料与发光器件为目标，以其内部空位缺陷的作用机制为研究核心。通过计算模拟研究了其卤化物离子迁移，并探究了其空位缺陷的形成条件及迁移机制，在此基础上采用溶液法制备了较高发光强度的Sn基钙钛矿纳米晶；在Sn基钙钛矿薄膜的研究中，以准二维Sn基钙钛矿为样本，优化了成膜工艺参数；针对2D PEA2SnI4薄膜的形貌和表面覆盖率较差问题，通过引入不同比例的胍离子，通过对其薄膜形貌、结构、光学和电学性能的对比，研究其对薄膜性能的影响，在引入最佳比例胍25%的同时，薄膜的结晶性、发光强度以及缺陷态浓度都得到了改善；进一步通过A位胍掺杂以及A位分子替代策略，改变钙钛矿有机成分的化学组成，实现了准二维Sn基钙钛矿材料的激子结合能提升，增强了其发光性能，并构筑了相应的电致发光器件，实现了效率的明显提升。依托项目共发表包括Matter、Advanced Functional Materials、Advanced Materials Interfaces等在内的SCI论文6篇，EI论文1篇，申请和授权国家发明专利3项。