Photoconducting pyrrone polymers

Abstract

SYNOPSISPyrrone polymers are found to exhibit substantial photoconductivity, photocurrentdark current ratios of up to 300 being obtained with incident intensities of pofychromatic light of 10-20 m.w./cm2. The condensation product obtained from 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 3,3',diaminobenzidine (BTDA-DAB) is about 4 to 5 times more photoresponsive than the product obtained from pyromellitic dianhydride and the same diamine (PMDA-DAB). Maximum photoresponse is obtained when samples are cured for at least 24 hours at 300°C. A linear dependence of photocurrent on voltage is found in the range 10' to 1 O5 volts/cm. The temperature dependence of photocurrent indicates that photocarriers are produced by more than one mechanism in the temperature range from room temperature to 300°C. Photoresponse is found to be maximum in the ultraviolet-visible region, with a peak response at 610 mp for PMDA-DAB and 550 mp for