Fabrication and characterization of multi-layer WSe₂ solar cells

Single atomic layer transition metal dichalcogenides (TMDs) and their van der Waals heterostructures have been explored extensively for ultrathin optoelectronic applications. However, optoelectronic devices made of multi-layer TMD thin-films have not been as extensively studied despite their strong absorption characteristics and wide absorption frequency. In this work, we present the electronic transport and photovoltaic characteristics of multilayer (~50 nm) WSe₂ devices. Multilayer WSe₂ is a high mobility ambipolar semiconductor which can be tuned by either electrostatic or chemical doping. In this work, we demonstrate a schottky WSe₂ solar cell using dissimilar metal contacts. The proof-of-concept dual-metal device shows an open-circuit voltage of >0.2 V, short circuit current density >4 mA/cm² and power conversion efficiency >2% under white light illumination with input power of 300 W/m². This study is being extended to explore methods to better optimize the WSe₂ based solar cell using experimental and modeling techniques. The results suggest that the device performance can be significantly improved by engineering the WSe₂ layer doping profile.