Photoresponse enhancement by anisotropic shape of a microscale freestanding solid-state bridge of a polythiophene-based polymer

This study shows another way to enhance the photoresponse of a conjugated polymer. This is confirmed by the wavelength and voltage-dependent photocurrent study of an anisotropic freestanding polymeric solid-state bridge, which was made of sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] between aluminum and copper wire electrodes. The field gradient induced by the anisotropic structure of the microscale polymer bridge enhanced the photoresponse by driving the photogenerated excitons toward the maximum field gradient region of the conical polymer bridge. The relatively high electric field strength at the narrow region efficiently broke excitons into electrons and holes. As a result, the photoresponse was enhanced.