  We theoretically study the efficiency limits and performance characteristics
of few-layer graphene-semiconductor solar cells (FGSCs) based on a Schottky
contact device structure. We model and compare the energy conversion efficiency
of various configurations by explicitly considering the non-Richardson
thermionic emission across few-layer graphene/semiconductor Schottky
heterostructures. The calculations reveal that ABA-stacked trilayer
graphene-silicon solar cell exhibits a maximal conversion efficiency exceeding
28\% due to a lower reversed saturation current when compared to that of the
ABC-stacking configuration. The thermal coefficients of PCE for ABA and ABC
stacking FGSCs are -0.064\%/K and -0.049\%/K, respectively. Our work offers
insights for optimal designs of graphene-based solar cells, thus paving a route
towards the design of high-performance FGSC for future nanoscale energy
converters.
