Enhanced photovoltaic effect in graphene-silicon Schottky junction under mechanical manipulation

Abstract

A graphene-silicon Schottky junction (GSJ), which has potentials of large-scale manufacturing and integration, can bring new opportunities to Schottky solar cells for photovoltaic (PV) power conversion. However, the essential power conversion limitation for these devices lies in a small open-circuit voltage (V o c), which depends on the Schottky barrier height. In this study, we introduce an electromechanical method based on a flexoelectric effect to enhance the PV efficiency in GSJ. By atomic force microscope (AFM) tip-based indentation and in situ current measurement, the current-voltage (I-V) responses under a flexoelectric strain gradient are obtained. The V o c is observed to increase for up to 20%, leading to an evident improvement of the power conversion efficiency. Our studies suggest that the strain gradient may offer unprecedented opportunities for the development of GSJ-based flexo-photovoltaic applications.