Layered transition metal dichalcogenide semiconductors are interesting for photovoltaics owing to their high solar absorbance and efficient carrier diffusion. Tungsten diselenide (WSe2), in particular, has emerged as a promising solar cell absorber. However, defective metal-semiconductor interfaces have restricted the power conversion efficiency (PCE) to approximately 6%. Here we report WSe2 photovoltaics with a record-high PCE of approximately 11% enabled by ultra-clean indium/gold (In/Au) van der Waals (vdW) contacts. Using grid-patterned top vdW electrodes, we demonstrate near-ideal diodes with a record-high on/off ratio of 1.0×109. Open-circuit voltage (VOC) of 571 +/- 9 mV, record-high short-circuit current density (JSC) of 27.19 +/- 0.45 mA cm−2 -- approaching the theoretical limit (34.5 mA cm−2) -- and fill factor of 69.2 +/- 0.7% resulting in PCE of 10.8 +/- 0.2% under 1-Sun illumination on large active area (approximately 0.13x0.13 mm2) devices have been realised. The excellent device performance is consistent with the high external quantum efficiency (up to approximately 93%) measured across a broad spectral range of 500-830 nm. Our results suggest that ultra-clean vdW contacts on WSe2 enable high-efficiency photovoltaics and form the foundation for further optimisation.
@article{arxiv.2506.14733,
title = {High-efficiency WSe$_2$ photovoltaics enabled by ultra-clean van der Waals contacts},
author = {Kamal Kumar Paul and Cullen Chosy and Soumya Sarkar and Zhuangnan Li and Han Yan and Ye Wang and Leyi Loh and Lixin Liu and Hu Young Jeong and Samuel D. Stranks and Yan Wang and Manish Chhowalla},
journal= {arXiv preprint arXiv:2506.14733},
year = {2025}
}
Comments
Main manuscript with four figures and supplementary figures