Optimization Study of a Novel Few-Layer Graphene/Silicon Quantum Dots/Silicon Heterojunction Solar Cell Through Opto-Electrical Modeling

FLG/SiQDs/Si heterojunction solar cells consisting of a layer of silicon quantum dots (SiQDs) sandwiched between few-layer graphene (FLG) and p- or n-type silicon is examined by a device physics model incorporated with the optical characteristics of FLG and SiQDs. FLG/SiQDs/Si solar cells enhance short-circuit current density, because charge carriers can tunnel through the energy states in SiQDs. Also, the quantum size effects result in a shift in the conduction and valence subband position of SiQDs which leads to a wide band gap and consequently the improvement of open-circuit voltage for FLG/SiQDs/Si solar cells. In addition, further improvement in the performance of FLG/SiQDs/Si solar cells can be obtained by tuning the size of SiQDs and FLG properties.