On the photoconductivity behavior of emeraldine-salt polyaniline films

Deep and shallow traps play a fundamental role in the photoresponse profile of organic devices. Here we present an investigation on emeraldine-salt polyaniline films concerning structural, optical, and electrical properties by X-rays diffraction, optical and electron microscopies, and optical spectroscopies as Fourier Transform Infrared Spectroscopy (FTIR), absorption, and photoluminescence (PL). Photoconductivity measurements show signatures related to localized states near-edge absorption and the efficient transition between polaron bands. The photoconductive profile is dependent on the excitation intensity and presents negative photoconductivity (NPC) for higher intensities. A rate equations model attributes the NPC to shallow traps while the increase of response and recovery times are associated with deep traps.