Synthesis and photoconductive characteristics of biphenylporphyrin‐containing poly(amic acid)s and polyimides

Abstract

AbstractThree series of biphenylporphyrin (BPP)‐containing poly(amic acid)s (PAAs) were synthesized and converted into heat‐treated polyimides (HPIs) and chemically treated polyimides (CPIs). Viscosity measurements, UV–vis and IR spectroscopies, as well as thermogravimetric analysis (TGA), were used to characterize the structures of the polymers. UV–vis spectra revealed that the BPP units formed aggregates in PAA and CPI films, rather than in HPI films. Photoinduced discharge was used to characterize the photoconductive properties of these polymer films. It was found that the photosensitivity was greatly enhanced by introducing BPP units into the polymer chains. For these three series of polymers, the photosensitivity increased in the order PAA < HPI < CPI according to the content of BPP in the polymers. The photoconductive characteristics were interpreted by the intrinsic π—π* process of BPP aggregation and the extrinsic process of charge‐transfer complex formation. The best photoconductive performances of the CPIs were attributed to the existence of two charge‐carrier‐generation processes. Copyright © 2004 Society of Chemical Industry