Abstract: A weakly coupled enhanced graphene film includes an enhanced graphene structure based on weak coupling, wherein the enhanced graphene structure based on weak coupling comprises a plurality of graphene units stacked vertically; the graphene unit is a single graphene sheet, or consists of two or more graphene sheets stacked in AB form; two vertically adjacent graphene units are weakly coupled, to promote the hot electron transition and increase the joint density of states, thereby increasing the number of hot electrons in high-energy states; the stacking direction of the graphene units in the graphene structure is in the thickness direction of the graphene film; and the graphene film enhances the accumulation of hot electrons in high-energy states by the enhanced graphene structure based on weak coupling.