基于预聚物的新型热致交联型空穴传输材料的设计、合成与光电性能研究

Organic light-emitting diodes (OLEDs) fabricated from solution processes such as ink-jet or screen printing show great merits and potential in large-size and flexible display application areas. In order to promote charge carrier injection, transportation and recombination, it is very critical to develop suitable solution-processable materials to form multilayer structure with clear interfaces.. In this project, we target on developing highly efficient thermal crosslinkable hole-transporting materials to solve the intermixing issue and attempt to work out new design strategy for solution-processable materials through investigating the relationships among molecular structure, material property and device performance. The “crosslinkable prepolymer” concept would be applied to prevent the existence of unreacted small-molecule residue and the optoelectronic properties of prepolymer could be manipulated through changing the components and the ratio. The crosslinking condition of benzocyclobutene could be optimized through structure modification. The packing of hole-transporting core units could be enhanced to benefit hole transportation by using the “crosslink through mainchain and transport among sidechain” approach. The objective of this project is to develop novel crosslinkable prepolymer-based hole-transporting materials with mild crosslinking condition and fast hole mobility to facilitate the preparation of highly efficient solution-processed multilayer OLEDs.

采用溶液加工工艺如喷墨打印、印刷等方式制备有机电致发光器件在大尺寸和柔性显示领域有着巨大的优势和潜力。为促进载流子注入、传输与复合平衡，开发合适的可溶液加工材料以制备界面清晰的多层器件结构非常重要。. 本项目拟以解决溶液加工型器件的层间混溶问题为切入点，以发展高效热致可交联空穴传输材料为研究目标，系统分析分子结构、材料性质与器件性能之间的关系，为设计可溶液加工材料提供新思路。采用“预聚物交联”的策略减少小分子残留并通过优化组分结构与比例调节材料的光电性能；以苯并环丁烯为交联单元，通过化学结构修饰优化其交联条件；采用“主链交联，侧链传输”的方式增强空穴传输单元的有效重叠以利于交联网状结构中空穴迁移，目的在于开发结构新颖的、交联条件温和、载流子迁移率高的交联型空穴传输材料，为构筑高效全溶液加工型器件提供材料保障。

针对溶液加工型OLED器件的层间混溶、载流子不平衡等关键科学问题，在本项目的支持下，项目负责人通过多种策略设计并合成了热致可交联空穴传输材料，并表征了这些材料的分子结构，研究了它们的热致交联性能与电致发光性能。开发的热致交联型空穴传输材料具有结构新颖、交联条件温和、载流子迁移率高等特点，以此制备的溶液加工型器件发光效率达到49.7 cd/A，启亮电压3.7 V，该指标与参比蒸镀器件性能相当（51.2 cd/A，3.3 V）。本项目为设计高效热致可交联空穴传输材料提供了一定的理论依据，为构筑高效全溶液加工型器件提供材料保障。