Use of graphene in combination with plasmonic metal nanoparticles to enhance the opto-electronic efficiency of thin-film solar cells

This study provides the response of placing a graphene layer along with plasmonic nanoparticles on top of Si substrate, which significantly increases the efficiency of the photo-voltaic (PV) cells. The advantage of using plasmonic nanoparticles has already been studied in previous studies. However, not much study has been done by using graphene layers in conjunction with plasmonic nanoparticles to improve the efficiency of solar cells. The reason behind choosing graphene is because of its high electrical and thermal conductivity, transparency, excellent flexibility, bending stability, and most importantly, thickness of one atom. Another big advantage is that graphene is inexpensive and widely available commercially. Therefore, in this study, the task was to place a layer of graphene on top of the Si substrate and at the top of this layer a single Ag nanoparticle was placed. Then, the optical absorption, short circuit current, open circuit voltage, output power, fill factor and near-field enhancementswere computed. These results due to the presence of a graphene layer below the Ag nanoparticle were compared with the results of placing Ag nanoparticle on top of the Si substrate without the presence of graphene layer. For both the cases, the diameter for Ag nanoparticle was kept at 20nm, 50nm and 100nm, respectively. After comparing these results, it was found that the use of graphene in addition to the plasmonic nanoparticles, as a layer on the Si substrate, significantly improves the efficiency of the PV cells. Further analysis was done by varying the thickness of graphene layer and it was found that the thickness of 2 nm graphene layer yields the optimum efficiency.