一种多层白色磷光有机电致发光器件的制备及性能研究

Fabrication of a new organic multilayer phosphorescent white-light-emitting device and evaluation of its characteristics

制备了一种结构为ITO/NPB/NPB:Ir(piq)2(acac)/CBP:TBPe/BAlq:rubrene/BAlq/Alq3/Mg:Ag的白色磷光有机电致发光器件.其中空穴传输型主体NPB掺杂磷光染料Ir(piq)2(acac)作为红色发光层,双载流子传输型主体4,4′-N,N′-dicarbazole-biphenyl(CBP)掺杂TBPe作为蓝色发光层,电子传输型主体材料BAlq掺杂rubrene作为绿色发光层.以上发光层夹于空穴传输层(NPB)与具有电子传输性的阻挡层(BALq)之间.由于各主体间异质结的存在,平衡了载流子在各发光层的分布,使得器件的制备具有较好的可重复性.通过控制各层厚度及染料掺杂量,可以得到高亮度的白光发射.所得白光器件启亮电压为4.5V,其具有的最大外量子效率和最高亮度分别为1.5%和16260cd/m2.当驱动电压从5.0V升高到20V时,器件色坐标由(0.396,0.432)改变为(0.411,0.414).由于该器件发射光谱主要由蓝(464nm)、绿(552nm)、红色(620nm)三个发射峰组成,与常见的白光器件相比,其更加适合与彩色滤色膜匹配得到三基色光,进而获得全色显示.

A novel organic phosphorescent white-light-emitting device （WOLED） with configuration of ITO/NPB/NPB：Ir（piq）2（acac）/CBP：TBPe/BAlq：rubrene/BAlq/Alq3/Mg：Ag is fabricated successfully, in which the phosphorescent dye （Ir（piq）2（acac）） doped into NPB （hole transport material）, fluorescent dye （TBPe） doped into CBP （ambipolar conductivity material） and another fluorescent dye （rubrene） doped into BALq （electron transport material） work as the red, blue and green emitting layer, respectively. The emitting layers are sandwiched between the undoped NPB and BALq layers. The charge distribution has been balanced for the introduction of heterojunctions between the different emitting layers, which results in a high fabrication reproducibility of the device. White emission is obtained by tuning the thickness and doping proportions of each layer. The device turns on at the driving voltage of 4.5 V. It shows a maximum external quantum efficiency and brightness of 1.5 % and 16260 cd/m^2, respectively. The Commission Internationale de l＇Eclairage （CIE） coordinates varies from （0.396, 0.432） at 5 V to （0.411, 0.414） at 20 V. The emission spectra of the device mainly consist of blue （464 nm）, green （552 nm） and red （620 nm） emissions peaks, which are particular suitable to be combined with color filters to obtain the three primary colors and further achieve full color displays.