Thiophene-Linked Polyphenylquinoxaline: A New Electron Transport Conjugated Polymer for Electroluminescent Devices

摘要

A new n-type conjugated polymer, poly2,2'-(THIOPHENE- 2,5-DIYL)-6,6'- BIS(3-PHENYLQUINOXALINE) (PTQx), was synthesized, characterized, and shown to be an excellent electron transport polymer for electroluminescent devices. PTQx thin films had a reversible electrochemical reduction but an irreversible oxidation, confirming its n-type nature. Electron affinity and ionization potential of PTQx thin films were estimated from cyclic voltammetry to be 3.0 and 5.54 eV, respectively. Poly(phenylene vinylene) (PPV) based light emitting diodes using PTQx as an electron transport layer, ITO/PPV/PTQx/Al, combined low turn-on voltage (3.6 eV) and high brightness (710 cd/sq m) with good efficiency (0.4%). The performance of PTQx as an electron transport material in electroluminescent devices was found to be far superior compared to all previously reported n-type polymers.