Synthesis of novel triphenylamine-based conjugated polyelectrolytes and their application as hole-transport layers in polymeric light-emitting diodes
作者:Wei Shi、Suqin Fan、Fei Huang、Wei Yang、Ransheng Liu、Yong Cao
DOI:10.1039/b603704f
日期:——
Alternating triphenylamine-based copolymers poly[N-(4-sulfonatobutyloxyphenyl)-4,4′-diphenylamine-alt-1,4-phenylene] sodium salt (PTPOBS) and poly[N-(4-sulfonatophenyl)-4,4′-diphenylamine-alt-N-(p-trifluoromethyl)phenyl-4,4′-diphenylamine] sodium salt (PTFTS) were synthesized via palladium-catalyzed Suzuki coupling reaction. These polymers are soluble only in polar solvents, such as dimethyl sulfoxide (DMSO) and a mixed solvent of methanol and N,N-dimethyl formamide (DMF), rather than in non-polar solvents such as toluene and xylene. The electrochemical and photophysical properties of the resulted copolymers were investigated. The HOMO levels of the polymers (−5.08 eV for PTPOBS and −5.24 eV for PTFTS) were close to the work function of PEDOT. The relatively high-lying LUMO levels (−2.21 eV for PTPOBS and −2.24 eV for PTFTS) revealed that they had good electron-blocking capabilities. Devices with a PTPOBS or PTFTS layer inserted between ITO or PEDOT and of red and green-emitting polymers showed lower turn-on voltages and enhanced efficiency compared with the reference devices composed of bare ITO or ITO/PEDOT as anode. These polymers can be used as an independent hole-transport/electron-blocking layer or in combination with a PEDOT layer for fabrication of multilayer devices without intermixing with the subsequent EL layer by solution processing in full-color display applications.
三苯胺基交替共聚物聚[N-(4-磺酸基丁氧基苯基)-4,4′-二苯胺-alt-1,4-亚苯]钠盐(PTPOBS)和聚[N-(4-磺酸基苯基)-4、通过钯催化的铃木偶联反应合成了聚[N-(4-磺酸基苯基)-4,4′-二苯胺-alt-N-(对三氟甲基)苯基-4,4′-二苯胺]钠盐(PTFTS)。这些聚合物只溶于极性溶剂,如二甲基亚砜(DMSO)以及甲醇和 N,N-二甲基甲酰胺(DMF)混合溶剂,而不溶于非极性溶剂,如甲苯和二甲苯。研究了所得共聚物的电化学和光物理特性。聚合物的 HOMO 电平(PTPOBS 为 -5.08 eV,PTFTS 为 -5.24 eV)接近 PEDOT 的功函数。相对较高的 LUMO 电平(PTPOBS 为 -2.21 eV,PTFTS 为 -2.24 eV)表明它们具有良好的电子阻断能力。与由裸 ITO 或作为阳极的 ITO/PEDOT 组成的参考器件相比,在 ITO 或 PEDOT 之间插入 PTPOBS 或 PTFTS 层以及红色和绿色发光聚合物的器件显示出更低的开启电压和更高的效率。在全彩显示应用中,这些聚合物可用作独立的空穴传输/电子阻挡层,也可与 PEDOT 层结合用于制造多层器件,而不会通过溶液处理与随后的 EL 层混合。