Performances enhancement of graphene/n-Si Schottky junction solar cells with dual-functional MoS2 interfacial layers

Highlights: • Large area MoS2 monolayers was prepared by sulfurizing pre-annealed Mo foil. • Reaction temperature and substrate structure have crucial influences on the growth mechanism. • MoS2 monolayers provided photon absorption and interfacial band engineering at heterojunction interface. • MoS2 interfacial layers enabled improved Schottky junction solar cells performance with a PCE up to 12.1%. -- Abstract: The preparation of vertical heterojunction structures using low dimensional films combined with strong light-absorption bulk material has dramatically accelerated the development of next-generation photovoltaic systems. Among the transition metal dichalcogenides, molybdenum disulfide (MoS₂) exhibits enormous potential for light-matter interactions and band nesting in photovoltaic devices, improving the absorption of photons and the generation of electron hole pairs. Unfortunately, the lateral scale of MoS₂ prepared by traditional methods is in the order of a few micrometers, which severely limits its industrial application. In this work, a novel method to synthesize MoS₂ monolayers on a large scale by directly sulfurizing molybdenum foil is presented. This method allows precise control of the layer number as well as the nondestructive transference of MoS₂ monolayers on various substrates. In this work, MoS₂ monolayers with optimized layer numbers are inserted at the graphene/n-Si interface and function as photon absorption and interfacial band engineering layers. This dramatically enhances the photovoltaic conversion efficiency of Schottky junction solar cells based on graphene. Finally, relatively high conversion efficiency of ~12% is successfully achieved in the heterojunction solar cells based on 2D materials. This work provides a promising new approach to obtaining 2D materials on a large scale, with potential for application in next-generation photovoltaic devices.