High-Efficiency WSe2 Photovoltaic Devices with Electron-Selective Contacts

A rapid surge in global energy consumption has led to a greater demand for renewable energy to overcome energy resource limitations and environmental problems. Recently, a number of van der Waals materials have been highlighted as efficient absorbers for very thin and highly efficient photovoltaic (PV) devices. Despite the predicted potential, achieving power conversion efficiencies (PCEs) above 5% in PV devices based on van der Waals materials has been challenging. Here, we demonstrate a vertical WSe2 PV device with a high PCE of 5.44% under one-sun AM1.5G illumination. We reveal the multifunctional nature of a tungsten oxide layer, which promotes a stronger internal electric field by overcoming limitations imposed by the Fermi-level pinning at WSe2 interfaces and acts as an electron-selective contact in combination with monolayer graphene. Together with the developed bottom contact scheme, this simple yet effective contact engineering method improves the PCE by more than five times.

Automated summary

Global energy consumption is increasing rapidly, leading to a higher demand for renewable energy. Van der Waals materials have recently been identified as efficient absorbers for thin and highly efficient photovoltaic devices. Researchers have achieved a significant improvement in power conversion efficiency in van der Waals-based photovoltaic devices by introducing a tungsten oxide layer and monolayer graphene.