Observation of carrier behavior in organic photo-conductor by transient space charge measurement

The space charge measurement technique has often been applied to insulating materials with low carrier mobility. However, some functional materials have high carrier mobility so that the evolution of space charge profile is hard to be observed. In this study, a new measurement method, which can measure the rapid transient of space charge, was proposed and applied to a photo-conductive material. The space charge after illumination by a light pulse was traced within the interval of several hundred microseconds. The shape of the transient current was well explained by the observed transient space charge.