Due to their extraordinarily large optical absorption coefficients, transition metal dichalcogenides (TMDs) are gaining more and more attention for photovoltaic applications. Improving the device performance of a TMD solar cell requires an optimal device architecture and reliable fabrication processes. Metal/WS2-multilayer/metal heterojunctions are fabricated using lithography-free processes. 20 nm thick WS2 flakes are exfoliated on template-stripped Ag bottom electrodes, and then 10 nm thick Au top electrodes with a diameter of 2 µm are evaporated on the WS2 surface using holey carbon films as shadow masks. Current-sensing atomic force microscope measurements reveal that the Au/WS2/Ag devices exhibit prominent rectifying characteristics, indicating the formation of Schottky diodes. The power conversion efficiency of the Schottky junction is as high as 5.0%, when illuminated by a light-emitting diode with a peak wavelength of 625 nm and a power density of 2.5 mW cm−2. These devices also possess broadband and incident-angle-insensitive absorption capability due to the very large refractive indices and extremely small thickness of the WS2 flakes. The simple fabrication procedures proposed in this work demonstrate high-performance and high-yield TMD photovoltaic devices.
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation of Korea Grant (2022R1A4A2000835, 2022R1A2B5B01002353, and 2018K1A4A3A01064272) and a National Key Research and Development Program of China (2018YFE0204003).
© 2023 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH.
- current-sensing atomic force microscope
- solar cell
- template-strip method
- vertical heterojunction