Graphene coupled with Pt cubic nanoparticles for high performance, airstable graphene-silicon solar cells

Graphene-silicon (Gr-Si) solar cells have been intensively investigated in recent years, which exhibits a potential application of two-dimensional materials in photovoltaics. However, the pristine Gr with low carrier concentration and therefore low work function is not suitable for the fabrication of high performance solar cells. Chemical doping is an effective way to improve the carrier concentration of Gr, but it is not stable and the efficiency of solar cell suffers heavy degradation. Here, we have developed a novel Gr-Si device structure with the coupling of two-dimensional Gr with zero-dimensional Pt nanoparticles on the top of bulk Si. The utilization of Pt nanoparticle can effectively enhance the sunlight absorption of solar cells by the plasmonic effect. Meanwhile, the carrier concentration and work function of Gr get greatly improved by physical doping of high-work-function Pt nanoparticle, and therefore the potential barrier at Gr-Si interface is significantly increased. More interestingly, the photo-induced doping of Pt nanoparticles for the Gr based on charge transfer has been observed for the devices under sunlight illumination. As a result, an efficiency of 7% has been achieved for our pristine solar cells, which is much higher than that of the control ones, similar to 4%. These devices with integration of zero-two-three dimensional materials have excellent air-stability, much more advantageous than the chemically doped ones. The efficiency of solar cell can further reach 10% by the application of spin-coated TiO2 antireflective film. These results point out a new route to the fabrication of high efficiency Gr-Si solar cells for photovoltaic application.