Organic semiconductor photocapacitive detectors

Abstract

In this study, the photocapacitive behavior of organic semiconductor, photosensitive material, poly-N-epoxypropylcarbazole (PEPC) doped with tetracyanoquinodimethane (TCNQ) and copper phthalocyanine (CuPc) were investigated. A sandwich type CG/PEPC-TCNQ/Al photocapacitive detector was fabricated by screen printing technology. Thin films of the copper phthalocyanine (CuPc) were deposited by vacuum evaporation on glass substrates with silver surface-type electrodes and a Ag/CuPc/Ag photo capacitive detector was fabricated. It was shown that under filament lamp illumination up to 2000 lx the capacitance of the CG/PEPC-TCNQ/Al photocapacitive detectors increased up to 5 % with respect to the dark condition. Similarly the capacitance of the Ag/CuPc/Ag photocapacitive detectors increased continuously up to 20% at 1000 lx relative to the dark condition. It is assumed that photocapacitive response of the detectors is associated with polarization due to the transfer of photo-generated electrons and holes.