Fig. 5. Optimization of the graphene (front contact) layer: (a) and (b) optimization of the graphene layer number, (c) and (d) optimization of the Φ (eV) of the graphene layer in which the parameters of n-MoS₂ and p-cSi are maintained at their best-optimized values, (e) and (f) optimization of the Φ (eV) of the graphene layer and (g) and (h) optimization of the thickness of a commercially available silicon wafer with practically available p-cSi parameters.