Enhanced photoconductivity in organic single-layered photoreceptors with bipolar charge transport materials

The organic single-layered photoreceptors (SLPRs) consisting of polycarbonate (PC) matrix containing dispersed N,N′-diethyl-4-aminobenzaldehyde-1-phenyl-1′-(α-naphthyl)-hydrazone (BAH) and 2,4,7-trinitrylfluorenone (TNF) as bipolar charge (hole and electron) transport materials, as well as oxotitanium phthalocyanine (TiOPc) as charge generation materials (CGMs), were prepared. The influence of organic electron transport material (ETM) on the photosensitivity in the photoreceptors was investigated. It was found that small amount of TNF (TNF/BAH ≤0.005) could improve the photosensitivity of photoreceptors greatly, i.e. the enhanced photoconductive effect, but the further increase of TNF concentration would lead to the decline of the photosensitivity. Differential scanning calorimeter (DSC), UV-Vis and cyclic voltammograms (CV) study showed that the enhanced photoconductivity might be resulted from the improvement of the separation efficiency of electron–hole pairs, and the decline of photosensitivity was due to the formation of the charge transfer complex (CTC) of TNF–BAH.