Surface photovoltage characterization of a ZnO nanowire array/CdS quantum dot heterogeneous film and its application for photovoltaic devices

Abstract

ZnO nanowire (NWs) arrays coated with CdS quantum dots (QDs) were successfully fabricated with a chemical bath deposition process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) have been utilized to characterize the samples. We have studied the processes of separation and recombination of the photo-generated charges in the visible region by surface photovoltage (SPV) and transient photovoltage (TPV) measurements. By controlling the amount of attached CdS QDs we found that the surface photovoltage characteristics change significantly. With a liquid electrolyte as the hole transport medium, the quantum dot sensitized nanowire solar cells (QDSSCs) exhibited short-circuit currents ranging from 0.8 to 2.6 mA cm(-2) and open-circuit voltages of 0.35-0.44 V when illuminated with light intensity 100 mW cm(-2). The relation between the performance of QDSSCs and their photovoltage characterization was also discussed.