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 PTP11

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 copolymers 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 multilayer 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.