红光磷光染料掺杂聚芴电致发光器件的研究

Red phosphorescence dye doped poly(9.9-dioctylfluorene) light emitting device

采用喹啉氮杂环类铱配合物[(PPQ)2Ir(acac)]为客体,以聚芴和2-(4-二苯基)-5-(4-叔丁基苯基)-1,3,4-噁二唑(PBD)为主体,研究了红光磷光有机电致发光的性质.样品的吸收光谱和发射光谱的结果表明(PPQ)2Ir(acac)和聚芴掺杂体系可以发生从主体到客体的有效Fo¨rster能量转移.然而,器件的电致发光光谱与样品的光致发光谱出现了明显的不同.在相同掺杂浓度下,前者更能实现纯的红光发射.这个结果表明,除了能量转移之外,客体的电荷捕获也是实现器件红色发光的原因之一.当(PPQ)2Ir(acac)掺杂浓度为1.0 wt%时,我们在10 V工作电压下得到了发光亮度为1 792 cd/m2,发光效率为6.16 cd/A的高性能红光器件.

The red phosphorescent organic light-emitting devices（OLEDs）employing bis（2,4-diphenylquinolyl-N,C2＇）iridium（acetylacetonate）[（PPQ）2Ir（acac）]as the guest and a blend of poly（9.9-dioctylfluorene）（PFO） with 2-（4-biphenyl）-5-（4-tert-butylphenyl）-1,3,4-oxadiazole（PBD）as the host have been reported.The absorption spectrum of（PPQ）2Ir（acac）and the photoluminescence（PL） spectra of PFO films doped with various concentrations of（PPQ）2Ir（acac） reveal the efficient Fo¨rster energy transfer from the singlet states of host to the triplet states of guest via intersystem crossing.However,the electroluminescence（EL） spectra of devices are different with the PL of samples,which EL show more pure red emitting than PL under the same concentrations of（PPQ）2Ir（acac）.This result demonstrates the charge trapping in the guest also is one main electroluminescence mechanism besides energy transfer.For the device doped with 1.0wt%（PPQ）2Ir（acac）,a luminous efficiency of 6.16 cd/A and a brightness of 1 792 cd/m2 are achieved at a voltage of 10 V.