Remarkable enhancement of graphene/Si Schottky junction solar cell performance with effective chemical treatments

Graphene has been employed in the preparation process of solar cells due to its unique properties. It has been combined with silicon (Si) substrates for preparing the top window structure of a graphene/n-Si Schottky junction solar cell. However, the usage of the mono-graphene layer results in a low fill factor of prepared samples. In addition, the residue of PMMA is one more reason for the low fill factor. Another disadvantage of reported devices is the poor stability of doped devices under ambient conditions. In this work, 2 low-cost and simple chemical treatments are employed to eliminate the residue of PMMA after the wet transfer procedure of graphene. Besides, the fill factor is significantly developed by transferring more than a residue-free graphene layer. An efficiency of 6% is obtained after preparing devices with 3 graphene layers, and the recorded efficiency of 14.2% is attained by the HNO₃ dopant. Additionally, doped devices show excessive stability for 2 months under ambient conditions, retaining around 96% of their initial efficiency. We attribute this development to the donation process of electrons achieved by chemical treatments to graphene. This work presents an approach for providing low-cost, simple, high performance and stable graphene/Si Schottky solar cells.