PHOTOCONDUCTIVITY AND PHOTOVOLTAIC EFFECT OF CHARGE-TRANSFER COMPLEX OF POLY[4-PHENYL-2,6-(P-PHENOXY)QUINOLINE] AND 2,3-DICHLORO-5,6-DICYANO-1,4-BENZOQUINONE

Abstract

A new polymer containing a heterocyclic quinoline unit in the main chain, poly[4-phenyl-2,6-(p-phenoxy)quinoline] (PQ), was synthesized by an acid-catalyzed self-condensation reaction. We have found that PQ, which is generally a good insulator itself, can show photoconductivity when doped with an electron acceptor. From the UV-VIS absorption spectra, we found that PQ can form a charge-transfer (CT) complex with an electron acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The CT complex of the PQ-DDQ mixture showed distinct photoconductivity. Employing the DDQ composition ranging from 5 to 10 wt %, the ratio of dark and photoconductivity was calculated to be about 1 : 100 at an applied electric field of 10(5) V/cm. Additionally, the bilayer sample of PQ/DDQ exhibited a significant photovoltaic effect. The photovoltaic current increased with increasing photointensity. The open-circuit voltage was measured ranging from 0.4 to 0.7 V and the photovoltaic conversion efficiency was calculated to be 10(-3)-10(-2)%. The PQ film treated with DDQ vapor showed a relatively higher photovoltaic effect than that of the sample treated with DDQ solution. (C) 1993 John Wiley & Sons, Inc.