磺酸盐取代三苯胺类共轭聚电解质的合成及应用研究

SYNTHESIS AND APPLICATIONS OF SULFONATE-SUBSTITUTED,TRIPHENYLAMINE-BASED CONJUGATED POLYELECTROLYTES

通过水相Suzuki偶合反应合成了两种磺酸盐基团取代的三苯胺类共轭聚电解质PTP11和PTP31,对其化学结构进行了表征.通过对其光学和电化学性能进行测试得知,此类聚合物具有和ITO功函数相近的HOMO能级及较高的LUMO能级.磺酸盐基团的存在使得此类聚电解质具有和电中性聚合物所不同的溶解性,当其作为空穴传输材料应用于多层结构的聚合物电致发光器件(PLED)中时,可有效避免空穴传输层-发光层之间的界面混溶问题.以这两种聚合物作为空穴传输材料应用于以PFO-DBT15为发光层的红光PLEDs中时,器件的性能得到了显著提高.此外,磺酸盐基团的不同取代方式会对器件的性能产生一定的影响.

Two kinds of sulfonate-substituted, triphenylamine-based conjugated polyelectrolytes, PTP11 and PTP31 were synthesized by water-phase Suzuki coupling reaction, and the control polymer PTPOBS was prepared using the same polymerization condition for comparison. The chemical structures of these polymers were verified by NMR and elemental analyses. The maximum absorptions of PTPll, PTP31 and PTPOBS in solid state appeared in the range of 361 -376 nm, with the optical bandgaps of 2.87- 2.93 eV. These polymers emitted blue light under the excitation at wavelength of their absorption maximum and showed the maximum emission at the region of 445 - 450 nm. Investigation of the electrochemical properties of these eopolymers suggests that they have HOMO levels （ - 5.08 - -5.16 eV） closing to the work function of ITO and possess relative high-lying LUMO levels （ - 2.23 - - 2.20 eV）. The solubility of these polymers is distinct from that of ＇neutral-charged＇ polymers due to the presence of anionic sulfonate groups in the side chain, thus the intermixing between hole-transport and emitting layers can be facilely avoided by choosing different solvents during the fabrication process of muhilayer PLEDs. The devices＇ performance was remarkably enhanced when using these polyelectrolytes as hole-transport layers in PFO-DBT15 based red-emitting PLEDs, and the device performance can be influenced by the different substitution manner of sulfonate groups. The external quantum efficiency of these devices at the current density of ca. 33.3 mA cm^-2 slightly decreases with the increasing composition ratio of directly sulfonated triphenylamine moiety in the polymers＇ backbone. The better device performance was obtained by using ITO/PTPOBS as anode, with the efficiency of 1.6% and brightness of 158 cd m^-2 .