Effect of the hole transport layer on photocarrier and transportation in the organic photo-electron conversion cell with a planar configuration

The organic photoreceptor devices were fabricated with a planar configuration and were investigated the photoelectric properties. The optimization of the device structure was examined in terms of decrease of the dark current. In this study, the Au or Al electrode was prepared with planar configuration on the substrate and then organic semiconductor layer was successively prepared. The organic layer of p- or n-type semiconductor was prepared and it was consecutively over-coated with n- or p-type semiconductor, respectively. Since the difference between the work functions of Au and Al, the influence of the contact barrier on dark current was expected. The influence of the contact between an organic layer and an electrode was examined. The results indicated that the dark current is mainly due to the hole injection from the electrode and transport into the p-type layer. In the device without the contact between p-type semiconductor and electrode, the performance of the device was considerably improved by reducing the dark current.