溶液方法制备的有机小分子OLED器件老化机理和稳定性研究

The two major challenges facing organic light-emitting devices (OLEDs) industry development are abtaining long lifetimes and low manufacturing costs. Solution processed small molecular OLEDs have attracted much attention because of their excellent performances, low-cost and simplified fabrication process. The performances of solution-processed small molecular OLEDs have been close to the vacuum-deposited counterparts, but the lifetimes of the devices are significantly shorter for the solution-processed devices than for the vacuum-processed ones. Therefore, it has important significance to study the degradation mechanisms and stability of solution-processed small molecular OLEDs. How to improve the stability of solution-processed small molecular devices has been urgent in the OLEDs industry development. Based on the needs, we intend to carry out experimental research on the stability of solution-processed small molecular OLEDs to explore the degradation mechanisms and to improve lifetime. In this project, the distinctive nature of the films fabricated using solution-processed small molecules will be investigated with a comparison of the vacuum-deposited films to explore its influence on the degradation of OLEDs. The electrical aging, dark spots growth, photodegradation and thermal aging of the solution-processed small molecular OLEDs will be also studied. Based on above research results, the degradation mechanisms of solution-processed small molecular OLEDs can be explored.Under the guidance of these degradation mechanisms,the stability of solution-processed small molecular OLEDs can be improved by using the thermal treated emitting layer, mixed-host emitting layer and multilayer structure. The successful project implementation will offer an important theoretical and practical foundation for improving the stability of organic electronic or optoelectronic devices based on solution process of small molecules,including OLEDs, organic memories, organic thin-film transistors and organic photovoltaic cells. It also provides some theoretical guidance for the industry development of low-cost, high efficiency and long lifetime OLEDs.

降低器件制备成本和提高器件工作寿命是有机电致发光器件（OLED）产业化发展所面临的两大难题。溶液方法制备有机小分子OLED器件由于其成本低、工艺简单、性能优越，受到人们的广泛关注，但器件的稳定性较差，距实用化仍有一定的距离。因此，针对溶液方法制备的有机小分子OLED器件的老化机理和稳定性问题开展研究具有重要意义。本项目通过研究溶液方法制备的有机小分子薄膜性能影响OLED器件老化的关键因素，以及器件的电学老化、黑点老化和光/热老化的成因，构建器件老化物理模型，揭示器件的老化机理。以此为指导，通过有针对性地调控发光层、主体材料和器件结构来改善器件的稳定性。通过本项目的实施，初步建立溶液方法制备有机小分子OLED器件的老化机理与提高这类器件稳定性的实践方法，为溶液方法制备的有机小分子OLED器件及其它有机半导体器件的稳定性研究奠定重要的理论和实践基础，为促进OLED器件产业化发展做出一定贡献。

溶液方法制备有机小分子OLED器件由于其成本低、工艺简单、性能优越，受到人们的广泛关注，器件的稳定性是亟待解决的关键问题。本项目以溶液方法制备的有机小分子OLED器件的老化机理和稳定性为研究目标，通过对有机小分子薄膜性质研究，获得薄膜本身性质影响器件老化的关键因素；研究器件的老化过程，分析影响器件老化的因素，揭示器件老化机理；探索提高器件稳定性的方法和途径，制备出低成本、长寿命的OLED器件。按照研究计划开展了三个方面的研究工作：（1）溶液方法制备的有机小分子薄膜性质研究；（2）溶液方法制备的有机小分子OLED器件老化机理研究；（3）溶液方法制备的有机小分子OLED器件稳定性改善研究。本项目进展顺利，取得了如下研究成果：（1）通过对溶液方法制备的有机小分子薄膜的成膜规律、形貌、折射率、光物理性质、结晶性质和电学性质的研究，获得了溶液方法制备的有机小分子薄膜的基本性质与规律；（2）通过对溶液方法制备的有机小分子OLED器件的黑点老化、水氧侵蚀老化和界面老化，获得器件的老化规律与机理；（3）通过在不同温度下热处理发光层，以及采用双极性混合主体结构提高OLED器件的稳定性，获得较长寿命的OLED器件。项目执行期间，发表标注项目资助的论文20篇，其中SCI收录论文18篇；参加学术会议15次；培养研究生6人，超额完成了预期指标。