Photoelectrochemical characterization of Si microwire array solar cells

Many proposed next-generation photovoltaic devices have complicated nano- and micro-structured architectures that are designed to simultaneously optimize carrier collection and light absorption. Characterization of the electrical properties of these highly structured materials can be challenging due to the difficulty of creating electrical contacts, as well as the need to decouple the properties of the contact from that of the semiconductor. Regenerative photoelectrochemistry is a powerful technique to characterize the electrical properties of such systems, providing a conformal liquid contact that can be ohmic or rectifying, depending on the system used. We demonstrate the use of the methyl viologen regenerative electrochemical system to characterize different stages of the fabrication of radial junction Si microwire (SiMW) solar cells. Photoelectrochemical characterization, combined with other more traditional measurements allows evaluation of how the different processing steps affect the device performance, without having to construct a fully integrated device. We describe the operating principle of this technique, and demonstrate that it can be applied to semiconductor materials with complex architectures.