Scanning probe photocurrent microscopy of polymer based devices

Summary form only given. Semiconducting polymer films when photoexcited with defined beam profiles generate excess charge carriers from the electronically excited state, which eventually spread over a volume exceeding the beam-sample cross-section. Our studies focuses on the length scales in model polymer systems, which are of fundamental importance in understanding the transport mechanisms and are crucial parameters for device development. A modified scanning photocurrent contrast microscopy technique was designed and implemented for these studies. The electron/hole transport processes can be independently evaluated by positioning the narrow-light beam selectively over the anode/cathode regions, enabling the estimation of the efficacy of hole transport vis-a-vis electron transport. Sizable photocurrent-signals between the electrodes are observed even at lateral distances several microns away from the counter electrode. These length scales in the first approximation corresponds to the mobility-lifetime product (mutau).