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

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 10₅ 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. © 1993 John Wiley & Sons, Inc.