摘要
Theoretically,blue phosphorescent materials are capable of achieving 100%internal quantum effi-ciency.Nevertheless,the mutual constraints among efficiency,color purity,and stability remain one of the key bottlenecks in the industrialization of organic light-emitting diodes(OLEDs).In addition,the design and application of host materials also exert a significant impact on the overall performance of blue light-emitting de-vices.To address this issue,this study constructs a series of host materials with high triplet energy levels by designing different connection modes,based on 9-phenylcarbazole and benzimidazole units.Through a combi-nation of theoretical and experimental approaches,the correlation between the chemical structure and perfor-mance has been unraveled.It is found that the designed and synthesized blue phosphorescent bipolar host ma-terials based on different biphenyl linking sites,i.e.,9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-bi-phenyl]-3-yl)-9H-carbazole(mCzmBI),9-(2'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-3-yl)-9H-carbazole(mCzoBI)and 9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-2-yl)-9H-carbazole(oCzmBI).The three compounds have a similar triplet energy level of 2.70 eV,accompanied with the glass transition temperatures of 92℃,103℃,and 93℃respectively.mCzmBI,mCzoBI and oCzmBI are regioiso-mers,but differ in the linking sites of carbazole and benzimidazole on the biphenyl linker.This difference in linking positions enables effective regulation of the host materials’properties.Constructed with the blue phos-phorescent material bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium(Ⅲ)(FIrpic)as the vip,the influence of the three hosts on device performance is clarified.Overall,the device using mCzmBI,a host linked by biphenyl at double meta-positions,achieved a maximum current efficiency of 24.9 cd·A^(-1)and a max-imum external quantum efficiency exceeding 12.8%,it also demonstrates low efficiency roll-off under highbrightness conditions.This work offers an effective strategy to the development of high-efficiency blue phospho-rescent hosts.
蓝色磷光材料理论上可实现100%的内量子效率,但其效率、色纯度、稳定性三者之间的相互制约关系仍是有机发光二极管(OLED)产业化进程中的关键瓶颈之一。此外,主体材料的设计和使用在很大程度上也影响了蓝光器件的整体性能。为此,本研究以9-苯基咔唑与苯并咪唑单元为基础,通过设计不同连接方式构建高三线态能级主体材料,采用理论与实验相结合的方法,探究材料的分子结构、光物理性能及器件应用性能,揭示其结构与性能之间的关联。实验结果表明,所设计并制备的基于不同联二苯基连接位点的蓝色磷光双极主体材料(即mCzmBI、mCzoBI与oCzmBI)均具有2.70 eV的三线态能级,三者的玻璃化转变温度分别为92℃、103℃和93℃。虽然mCzmBI、mCzoBI与oCzmBI互为同分异构体,但其咔唑基团与苯并咪唑基团在联苯基团上的连接位点不同,这种连接位点的差异可以很好地实现对主体材料性能的有效调控。以经典蓝光磷光材料FIrpic为客体,分别研究三种主体对器件性能的影响机制。其中,以联二苯基双间位连接的主体mCzmBI所构筑的器件最大电流效率达24.9 cd·A^(-1),最大外量子效率超过12.8%,并在高亮度环境下表现出较低的效率滚降。该研究为高效蓝光磷光主体的开发提供了一种有效的策略。
出处
《发光学报》
北大核心
2025年第12期2293-2301,共9页
Chinese Journal of Luminescence
基金
深圳市科技计划项目(20231127123500001,20231127120511001,JCYJ20240813143022029)
深圳信息职业技术大学项目(TD2024E002,SZIIT2025KJ045,SZIIT2024KJ021)
国家自然科学基金(52373195,62175189,22405177)
广东省基础研究与应用基础研究基金(20205A1515010054)。
