Efficiency improvement of graphene/silicon Schottky junction solar cell using diffraction gratings

Abstract

This study investigated the performance of graphene/silicon Schottky junction solar cells and presented two structures based on graphene diffraction gratings to significantly enhance the efficiency of the cells. Rectangular and staircase graphene gratings were employed as the junction pairs for silicon. The main structure and the proposed structures were then investigated at different temperatures, silicon thicknesses, and doping levels. The results showed that graphene grating significantly increased the internal electric field and width of the depletion region compared to the main structure. Moreover, the graphene-silicon interface area was increased at the contact point, consequently decreasing the dangling bonds. These regions also act as anti-reflectors and reduce the reflection of sunlight. The efficiency of the proposed structures, thanks to the aforementioned features, has been reported to be three-fold greater than the main structure. For instance, at the temperature of 300 K, doping level of 1 × 1017 cm−3 and silicon thickness of 500 nm, the short-circuit current, open-circuit voltage, fill factor, and efficiency of the main structure were obtained as 20.3 mA/cm2, 0.154 V, 57.3%, and 1.8%, respectively. For the same conditions, these figures were obtained as 22.4 mA/cm2, 0.398 V, 73%, and 6.54% for the rectangular graphene grating, and 20.8 mA/cm2, 0.397 V, 73%, and 6.08% for the staircase graphene grating, respectively.