Project 4: High-efficiency photovoltaic cells based on atomically thin monolayer p-n junction
PI: Lance Li, Aram Amassian, Thomas Anthopoulos
Transition metal dichalcogenide (TMD) monolayers exhibit wide applications in optoelectronics and flexible electronics owing to their unique band structure, direct gap property, and excellent bendability. The formation of lateral p-n junctions on a TMD monolayer enables the functionalities such as current rectifying, light emitting and photon harvesting. We shall develop the method to form spatially distributed up and down polarizations in ferroelectric films, where these polarized domains can induce p- and n- carriers in WSe2. The design in the following figure shall lead to reliable diode characteristics and photovoltaic effects across the WSe2 monolayer p-n junction without the need to apply external gate voltages. Since the p- and n- structures are seamlessly jointed at the same atomic plane, the electron and hole separation is expected to be highly efficient. Meanwhile, we also like to extend the project to explore the possibility of using vertical p-n junctions formed in between p-type thin perovskite layer and n-type 2D material. Such structure shall be able to absorb more sunlight for better solar cell PCE.
In addition to the study of 2D materials for solar cell applications, an alternative device architecture based on asymmetric co-planar metal nanogap anode/cathode electrodes, will also be developed and studied. Large aspect-ratio asymmetric electrodes will be patterned using the recently developed adhesion lithography (a-Lith) method onto various substrate materials including plastic foils. The 2D photoactive nanosheets shall be integrated with the nanogap electrodes for photovoltaic and photodetector applications. Meanwhile, STM shall be adopted to characterize the atomic/molecular structures of these 2D nanosheets.