三元铱配合物磷光体系的白光有机电致发光器件光谱特性研究

Spectral Characteristics of White Organic Light-Emitting Devices Based on Phosphorescent System of Three Iridium Chelates

将黄光磷光材料bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2’]iridium(acetylacetonate)[(t-bt)2Ir(acac)]超薄层作为黄光发光层,两个蓝光磷光染料iridium(Ⅲ)bis(4’,6’-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate(FIr6)和bis[(4,6-difluorophenyl)-pyridinato-N,C2’](picolinate)iridium(Ⅲ)(FIrpic)掺杂层作为蓝光发光层,制备了三元发光层的白光有机电致发光器件。该器件具有三元磷光染料分子协同发光特性,并且利用合适厚度的隔层,将三线态激子束缚在各自激子复合区域内,获得了稳定电致发光光谱,CIE色坐标为(0.29±0.01,0.34±0.01),处于理想的白光区域。通过器件电学特性的测试,验证了磷光染料在三元发光层器件中电致发光作用的机理,同时结果表明,三元发光层器件由于稳定的激子复合区域而有效减弱了器件效率滚降现象。

A white organic light-emitting device（WOLED） with a yellow phosphorescence material,bis[2-（4-tertbutylphenyl）benzothiazolato-N,C2＇] iridium（acetylacetonate） [（t-bt）2Ir（acac）],and two blue phosphorescence materials,iridium（Ⅲ） bis（4＇,6＇-difluorophenylpyridinato）tetrakis（1-pyrazolyl）borate（FIr6） and bis[（4,6-difluorophenyl）-pyridinato-N,C2＇]（picolinate） iridium（Ⅲ）（FIrpic）,were fabricated.Stable white emission was realized by using undoped ultrathin yellow emissive layer（EML）,two doped blue EMLs together with the proper thickness of an interlayer confining the exciton.The WOLED performed pure white light emission with the Commissions Internationale de l＇Eclairage（CIE） coordinates of（0.29±0.01,0.34±0.01） from 6 to 14 V.Moreover,electroluminescence（EL） characteristics of the devices were also studied to verify the emissive mechanism from a phosphorescent system consisting of three iridium chelates.Also,the results showed that the triple-phosphor-element EMLs WOLED had lower efficiency roll-off owing to the stable recombination zone.