Transient and steady state lateral charge transport in polymeric semiconductors

Abstract

The Lateral photovoltaic effect (LPE) has been used as an effective tool to probe the dynamics of photogenerated charge carriers in conjugated polymer based optoelectronic devices. In this paper, we analyze the time-dependence of LPE in a position sensing device geometry using a discrete circuit equivalent model coupled with a spreading impedance approach. We elucidate the dependence of the lateral photovoltage (LPV) on the position, intensity and the modulation frequency (ω c ) of the light beam. Previous experimental results for the position and ω c dependence of the LPV in the steady state are successfully reproduced within the present approach. We predict a clear knee-like feature in the transient regime of the LPV for high photocurrent values. This feature prompts us to propose that the response time of the organic position sensing device decreases sharply with increasing incident intensity.