石墨烯量子点-银异质结表面等离激元共振增强共轭聚合物发光研究

More advanced colloidal Ag nanoparticle design and synthesis offers a tremendous potential for further boosting PLED performances. However, the noble metal nanoparticles cover the substrate with much lower densities and are usually dentrimental to carrier transport properties, limiting their applications in polymer light-emitting devices. This project aims to prepare graphene-quantum-dot-supported silver nanoparticles (GQDs–Ag) using the graphene quantum dots (GQDs) both as a reducing agent and a template. The size and surface functional group of GQDs, as well as reduction process is tailored to set the sizes and numbers of Ag particles grown on carbon supports, and hence to control electronic coupling between Ag–Ag particles, and ultimately to control the plasmonic modes and intensities. Besides, the project also investigates the effect of GQDs-Ag on the conjugated polymer’s absorption intensity, emission intensity, fluorescence quantum efficiency and exciton lifetime. The issue of spontaneous emission rate of conjugated polymer is engineered by the sizes and numbers of GQDs-supported silver nanoparticles, by varying the distance between GQDs-Ag and the conjugated polymer, and by conjugated polymer films mophology, has also been studied. The composite film used in PLED device is optimized according to PL studies, and the ability of GQDs-Ag heterostructure is evaluated to enhance luminous efficiency of PLED. This project not only helps to understand the light-matter interaction in the nanocale, but also provides important basis for designing highly efficient PLED devices.

先进胶体金属纳米粒子的设计与合成为提高聚合物发光器件效率提供了巨大的潜力，针对该类聚合物发光器件中存在添加的金属纳米粒子表面覆盖率低以及添加后影响载流子传输等问题，本项目拟以石墨烯量子点（GQDs）为模板还原制备GQDs负载银纳米粒子的GQDs-Ag异质结。通过控制GQDs模板的尺寸和表面功能基团，调控GQDs负载银纳米粒子的尺寸和密度以及Ag-Ag间的电磁耦合作用，进而实现对表面等离激元共振模式和强度的调控。在此基础上，研究GQDs-Ag异质结对共轭聚合物光吸收强度、发射强度、荧光量子效率以及激子寿命的影响，通过控制GQDs-Ag与聚合物分子之间的距离以及聚合物薄膜形态，实现对共轭聚合物自发发射速率的调控，进而提高GQDs-Ag纳米异质结增强聚合物发光器件效率的能力。本项目研究成果不仅有助于加深对纳米尺度下光与物质之间相互作用的认识，也为设计新型高效的聚合物发光器件提供依据。

本项目旨在开发具有协同表面等离激元活性的石墨烯量子点-银(GQDs-Ag)异质结，探索其与共轭聚合物激子之间的近场耦合效应。首先，通过广泛研究柠檬酸基、碳纤维基和氧化石墨烯基纳米点的结构与发光性质之间的关系，详细表征各类GQDs的复杂化学结构，提出超分子和多重准分子结构在纳米点形态和发光性质的关键作用，从而为合成GQDs-Ag异质结奠定扎实基础。然后，通过控制GQDs模板的物理化学结构，控制负载Ag纳米粒子的尺寸和密度，实现了异质结表面等离激元的有效调控。将多种发光共轭聚合物组装在GQDs-Ag单层上制备耦合薄膜，研究共轭聚合物化学结构以及异质结在基底上的覆盖率对耦合薄膜光吸收速率、荧光量子产率以及激子衰变速率的影响。通过层层自组装精确控制异质结与聚合物之间的距离，研究了GQDs-Ag异质结对共轭聚合物发光的局域场增强效应，证实异质结表面等离子可有效调控共轭聚合物自发辐射过程。本项目的研究为表面等离子激元增强光电器件设计提供了有力支持，同时也拓宽了异质结表面等离激元的应用领域。