Regulating electronic properties of graphene sheet via n-type doping for solar cells applications

Solar energy can be utilized by electronic device known as solar cells which are then used to power various equipment as well as batteries. The conventional semiconductor used in solar cell is silicon and it has a bandgap of 1.4 eV. However, for efficient photovoltaic phenomena along with superior performance of solar cell, we require a novel semiconductor with smaller bandgap ideally up to this range. Hence, in this present work, attempts have been made to regulate the electronic bandgap in graphene sheet to use it for solar cell application. The in-depth analysis of electronic properties considering the band structure, density of states and geometrical stability on the basis of cohesive energy has been examined. Two n-type dopants, Phosphorus and Nitrogen are substituted in graphene sheet and investigations are reckoned in the frame work of density functional theory. The controlled tuning of bandgap is performed by varying dopant concentration at 5.55%, 8.83% and 11.11%. Our findings show that doping induces bandgap in both cases and requirement of smaller bandgap is achieved. For phosphorus doping, bandgap of 0.3 eV for 11.11% and for nitrogen doping, bandgap of 1.5 eV is achieved. Furthermore, the electrical properties are evaluated by calculating conductance for individual dopant with varying percentage. Finally, our outcome shows that the phosphorus-doped graphene is more favourable in comparison to nitrogen doped as it provides bandgap while not reducing conductance to that extent. Thus, this analysis will enhance the scope of doped graphene in solar cells application.