Supervisors: Tom Hoekstra, Peter Schall, and Jorik van de Groep
Since the isolation of graphene in 2004, more than two thousand layered 2D materials have been identified. These materials can be exfoliated from bulk down to atomically thin monolayers, which exhibit unique optical and electronic properties, including stable excitons at room temperature. By employing a deterministic stamping technique, different 2D semiconductors can be stacked on top of each other to create ultra-thin heterojunction solar cells without the need for doping. However, the role of excitons in the photovoltaic performance of these 2D photovoltaic devices remains unexplored.
In this joint project, you will use a stamping technique to fabricate your own micro-scale 2D photovoltaic devices by stacking different 2D semiconductors. Using these devices, you will study the role of excitons in the photocurrent generation. Specifically, you will combine materials that host inter-layer excitons, i.e., with the electron in one layer and the hole in other. These inter-layer excitons have long lifetimes and provide new ways to steer and absorb light at the atomic scale. You will use photoluminescence spectroscopy and time-resolved emission experiments to study the exciton dynamics, and then design micro-scale photovoltaic devices to efficiently dissociate these excitons in novel 2D heterostructures.