Crystalline Si/Graphene Quantum Dots Heterojunction Solar Cells

Graphene quantum dots (GQDs) possess extraordinary optical and electrical properties and show great potential in energy applications. Here, with combing of crystalline silicon (c-Si) and GQDs, a new type of solar cells based on the c-Si/GQDs heterojunction was developed. Thanks to the unique band structure of GQDs, photogenerated electron–hole pairs could be effectively separated at the junction interface. The GQDs also served as an electron blocking layer to further prevent the carrier recombination at the anode. These characteristics endow the heterojunction solar cells with much enhanced photovoltaic performance compared to the device counterparts without GQDs or with graphene oxide sheets. Eventually, an optimum power conversion efficiency of 6.63% was obtained by tuning the GQDs size and layer thickness. Our results demonstrate the great potential of the c-Si/GQDs heterojunctions in future low-cost and high-efficiency solar cells.