A new silole monomer with two 4-(N,N-dimethylamino)phenyl substitutions on silicon atom as designed and synthesized. Three copolymers PF-N-HPS1, PF-N-HPS10 and PF-N-HPS20 were then obtained by copolymerizations of 2,7-fluorene derivatives with the silole monomer at feed ratios of 1%, 10%, and 20%. Their UV-vis absorption, electrochemical, photoluminescent, and electroluminescent (EL) properties were investigated. PF-N-HPS possessed HOMO levels of −5.25–−5.58 eV, and showed green emissions. Using PF-N-HPS as the emissive layer, three different polymer light-emitting diodes were fabricated as device A with ITO/PEDOT/PF-N-HPS/Al, device B with ITO/PEDOT/PF-N-HPS/Ba/Al, and device C with ITO/PEDOT/PF-N-HPS/TPBI/Ba/Al. For the device A, PF-N-HPS only showed very low EL efficiency of 0.06–0.33 cd/A, indicating that the Al cathode could not inject electron efficiently to the emissive polymers containing the 4-(N,N-dimethylamino)phenyl groups. For the device B, low work function Ba supplied better electron injections, and the EL efficiency could be improved to 0.85–1.44 cd/A. TPBI with a deep HOMO level of −6.2 eV could enhance electron transport and hole blocking. Thus modified recombinations and largely elevated EL efficiency of 4.56–7.96 cd/A were achieved for the device C. The separation of the emissive layer and metal cathode with the TPBI layer may also suppress exciton quenching at the cathode interface.
设计并合成了一种在
硅原子上有两个 4-(N,N-二甲基
氨基)苯基取代的新型
硅烯单体。然后,2,7-
芴衍
生物与
硅烯单体以 1%、10% 和 20% 的进料比共聚,得到了三种共聚物 PF-N-HPS1、PF-N-HPS10 和 PF-N-HPS20。研究了它们的紫外可见吸收、电
化学、光致发光和电致发光(EL)特性。PF-N-HPS的HOMO
水平为-5.25-5.58 eV,并显示出绿色发射。利用 PF-N-HPS 作为发光层,制备了三种不同的聚合物发光二极管,分别是采用 ITO/PEDOT/PF-N-HPS/Al 的 A 器件、采用 ITO/PEDOT/PF-N-HPS/Ba/Al 的 B 器件和采用 ITO/PEDOT/PF-N-HPS/TPBI/Ba/Al 的 C 器件。在装置 A 中,PF-N-HPS 的电致发光效率很低,仅为 0.06-0.33 cd/A,这表明铝阴极不能有效地向含有 4-(N,N-二甲基
氨基)苯基基团的发光聚合物注入电子。对于装置 B,低功函数 Ba 能提供更好的电子注入,EL 效率可提高到 0.85-1.44 cd/A。具有-6.2 eV深HOMO电平的TPBI可增强电子传输和空穴阻滞。TPBI 层将发射层和
金属阴极隔开,还可以抑制阴极界面的激子淬灭。