Improved efficiency of graphene/Si Schottky junction solar cell based on back contact structure and DUV treatment

Abstract

A graphene/Si Schottky junction solar cell is commonly fabricated by using the top-window structure. However, reported devices have many drawbacks such as a small active area of 0.11 cm², s-shape in the J-V curves, recombination process of charge carriers at the graphene/textured Si interface, high cost and a complex fabrication process. Here, we report a novel graphene/Si Schottky junction solar cell with a back contact-structure, which has benefits of a simpler fabrication process, lower fabrication cost, and larger active area in comparison with a device fabricated with the previous structure. Additionally, we found that the PMMA residue left on graphene surfaces is the key to eliminate the s-shape in the J-V curves. Thus, the deep UV treatment of the CVD graphene is applied within the wet transfer process to effectively remove the PMMA residue, suppress the behavior of s-shaped kink in J-V curves and enhance the solar cell efficiency. As a result, the recorded power conversion efficiency of 10% is achieved for graphene/textured Si devices without chemical doping and anti-reflection coating, and this value is improved to 14.1% after applying chemical doping. Doped devices also show great stability and retain 84% of the efficiency after 9 days storage in air.