2D/3D Heterostructure Interface Design and Property Modification

2D/3D Heterostructure Solar Cells have attracted numerous attention due to its potential to be an alternative to the silicon (Si) Wafer-based photovoltaic technologies. However, most 2D/3D Heterojunction photovoltaic cells suffer from long-term instability in power conversion efficiency. This is mainly due to the interfacial charge carrier recombination owing to the low 2D/3D built-in electric field. Therefore, it is critical to overcome these challenges via interfacial engineering. Here in my thesis, I have introduced 2D thin film like hexagonal boron nitride (h-BN) and ultrananocrystallinediamond (UNCD) as tunneling inter-layer in Graphene/Si heterojunctions. The 2D/2D/3D architecture of graphene/h-BN/Si or graphene/UNCD/Si forms a metal-insulator-semiconductor (MIS)-type junction, where h-BN and UNCD act as an electron-blocking or hole-transporting medium and they avoid interfacial charge carrier recombination. A 4-fold increase in open-circuit voltage (VOC) is found for graphene/h-BN/Si heterojunction cell (0.52 V) in contrast to the graphene/Si cell (0.13 V), which is due to the increase in the effective Schottky barrier height and hence built-in electric voltage.