(515e) Achieving High Open-Circuit Voltage in Graphene/Silicon Photovoltaic Cells with h-BN Tunneling Layer

Graphene-on-Silicon (G/Si) Solar Cell has attracted numerous interest due to its potential to be an alternative to the Si wafer-based photovoltaic technologies. However, such 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 G/Si Schottky barrier height. Therefore, it is critical to overcome these challenges via interfacial engineering. Here we have introduced two-dimensional (2D) hexagonal boron nitride (h-BN) crystal as a tunneling inter-layer in graphene/Si heterojunctions. Thin films of h-BN is directly synthesized on lightly-doped Si surface via bottom-up chemical-surface-adsorption strategy followed by the transfer of chemical vapor deposited graphene. The 2D/2D/3D architecture of Graphene/h-BN/Silicon forms a metal-insulator-semiconductor (MIS)-type junction, where h-BN acts as an electron-blocking or hole-transporting medium and it avoids interfacial charge carrier recombination. An increased open-circuit voltage (V_OC) is found and this may be due to the decrease in interfacial charge carrier recombination and increase in light generated current.