PLED devices containing triphenylamine-derived polyurethanes as hole-transporting layers exhibit high current efficiencies
作者:Cheng-Hsiu Ku、Chao-Hui Kuo、Chih-Yi Chen、Man-Kit Leung、Kuo-Huang Hsieh
DOI:10.1039/b715929c
日期:——
The innovative polyurethane-type polymers from a triphenylamine derivative, [N,N′-bis(4-hydroxyphenyl)-N,N′-diphenylbenzidine] (TPA) and a carbazole derivative, [9-butyl-3,6-bis(4-hydroxyphenyl)carbazole] (Cz) can be linked through isophorone diisocyanate (IPDI) bridges and incorporated as hole-transporting layers in high-performance PLED devices. The TPA–IPDI–Cz type of polyurethane (PU) materials (P1–P5) showed superb hole injection and transport properties based on the results of the hole-only-device study. We prepared the devices in two kinds of configuration: system (1) Indium Tin Oxide (ITO)/PU (20 nm)/Iridium(III) bis(2-phenylpyridine), [Ir(ppy)3] + 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (t-PBD) + polyvinylcarbazole (PVK)] (50 nm)/Mg (10 nm)/Ag (100 nm), for the device with P1 (DP1), the brightness increased to 14 000 cd m−2, the current efficiency rose to 13.4 cd A−1, and the turn-on voltage was reduced to 21 V (at 100 cd m−2). In system (2) ITO/PEDOT–PSS (30 nm)/PU (20 nm)/[Ir(ppy)3 + t-PBD + PVK] (50 nm)/Mg (10 nm)/Ag (100 nm), with PEDOT–PSS as the hole-injection layer, was compared to the standard device (S2) having the configuration ITO/PEDOT–PSS (50 nm)/[Ir(ppy)3 + t-PBD + PVK] (50 nm)/Mg (10 nm)/Ag (100 nm); the brightness of the double layer device with P5 (DDP5) increased to 12 500 cd m−2 and the current efficiency dramatically rose to 34.7 cd A−1, compared with values of 6250 cd m−2 and 21.8 cd A−1, respectively, for S2.
由三苯胺衍生物[N,N′-双(4-羟基苯基)-N,N′-二苯基苯胺](TPA)和咔唑衍生物[9-丁基-3,6-双(4-羟基苯基)咔唑](Cz)制成的创新聚氨酯类聚合物可以通过异佛尔酮二异氰酸酯(IPDI)桥连并作为高性能PLED器件中的载流子传输层。TPA–IPDI–Cz类型的聚氨酯(PU)材料(P1–P5)在仅孔导电器件研究中的结果显示出优异的孔注入和传输特性。我们准备了两种配置的器件:系统(1)铟锡氧化物(ITO)/PU(20 nm)/铱(III)双(2-苯基吡啶), [Ir(ppy)3] + 2-(4-联苯)-5-(4-叔丁基苯基)-1,3,4-噁二唑(t-PBD) + 聚乙烯咔唑(PVK)}(50 nm)/镁(10 nm)/银(100 nm),使用P1(DP1)得到的亮度提高到14,000 cd m−2,电流效率上升到13.4 cd A−1,开启电压降低到21 V(在100 cd m−2时)。在系统(2)ITO/PEDOT–PSS(30 nm)/PU(20 nm)/[Ir(ppy)3 + t-PBD + PVK](50 nm)/镁(10 nm)/银(100 nm)中,PEDOT–PSS作为孔注入层,与标准器件(S2)进行比较,S2的配置为ITO/PEDOT–PSS(50 nm)/[Ir(ppy)3 + t-PBD + PVK](50 nm)/镁(10 nm)/银(100 nm);使用P5(DDP5)时,双层器件的亮度增加到12,500 cd m−2,电流效率显著提高到34.7 cd A−1,而S2的值分别为6250 cd m−2和21.8 cd A−1。