Advanced interface modelling of n-Si/HNO3 doped graphene solar cells to identify pathways to high efficiency

•It’s physically more accurate to model graphene/silicon junction as a heterojunction rather than simplified Schottky junction.•The model allows detailed investigation on the sensitivity of solar cell performance to the properties of graphene, which was not possible in the simplified Schottky junction approach.•The cell performance can be improved to up to 22.5% after optimizations of the antireflection coatings and the rear structure.