一种含液晶基元的新型铱配合物的合成与发光性能研究

摘要

为了实现溶液化制备有机电致发光器件(OLED),制备和应用具有高溶解性的有机电致发光材料是重要的手段之一。本工作设计和合成了一种含液晶分子中常用的丙基双环己基二氟苯基结构单元的配体及其铱配合物 Ir(cfpp)2(acac)(cfpp ＝2-(2,3-二氟-5-[trans,trans-4′-丙基-(1,1′-双环己基)]苯基)吡啶)；acac ＝乙酰丙酮负离子)。以其作为绿色发光掺杂材料,按照2％、4％和8％的掺杂含量旋涂制备了 OLED 器件,器件结构为 ITO/PEDOT∶PSS/PVK∶PBD∶Ir(cfpp)2(acac)/ TPBi / LiF / Al。当掺杂浓度为8％时,器件的最大发射波长为524 nm,最大发光亮度达到3600 cd/m2；当电流密度为20 mA/cm2时,最大电流效率和功率效率分别为2．0 cd/A 和0．6 lm/W,具有较强的电致发光特性。研究结果表明,应用含液晶结构单元设计和合成高溶解性的有机电致发光材料是可行的研究思路,为制备可旋涂有机电致发光材料提供了新方法。%In order to realize the fabrication of the OLEDs by solution-processing,synthesis and appli-cation of highly soluble organic electroluminescent materials is one of the important ways.In the pres-ent work,a ligand containing a structural moiety of 4′-n-propyl-(1,1′-bicyclohexyl)-4-difluorophenyl commonly used in liquid crystal molecules and its iridium complex,Ir(cfpp)2 (acac)(cfpp = 2-[2,3-difluoro-5-(trans,trans-4"-n-propyl-(1",1′-bicyclohexyl)-4′-yl)phenylpyridine);acac = acetylaceto-nate)were synthesized.The synthesized iridium complex was used as a green light-emitting dopant material with 2%,4% and 8% doping concentration (mass fraction)in emissive layer to fabricate OLED devices by spin-coating method,and the structure of OLED device comprises of ITO/PEDOT∶PSS/PVK∶PBD∶Ir(cfpp)2 (acac)/ TPBi / LiF / Al.When the doping concentration was 8%,the maximum emission wavelength of OLED device appears at 524 nm with the maximum brightness of 3 500 cd/m2 . When the current density is 20 mA/cm2 ,the maximum current efficiency and power efficiency of the device are 2.0 cd/A and 0.6 lm/W,respectively,indicating that the prepared device shows the inter-esting characteristics of electroluminescence.The obtained results imply that it is a practical concept to design and synthesize the soluble organic electroluminescent materials for spin-coating procedure by introduction of the structural moiety of liquid crystal molecules.