2021/06/24 by Koosha Nassiri Nazif, Alwin Daus, Jiho Hong +13 · 1 citation
Physics and Astronomy · #physics.app-ph #cond-mat.mtrl-sci
paper · pdf · doi:10.1038/s41467-021-27195-7
published as Nature Communications 12, 7034 (2021) · 39 pages; v2: some references reformatted
arxiv created 2021/06/24 · arxiv updated 2022/01/24
Semiconducting transition metal dichalcogenides (TMDs) are promising for flexible high-specific-power photovoltaics due to their ultrahigh optical absorption coefficients, desirable band gaps and self-passivated surfaces. However, challenges such as Fermi-level pinning at the metal contact-TMD interface and the inapplicability of traditional doping schemes have prevented most TMD solar cells from exceeding 2% power conversion efficiency (PCE). In addition, fabrication on flexible substrates tends to contaminate or damage TMD interfaces, further reducing performance. Here, we address these fundamental issues by employing: 1) transparent graphene contacts to mitigate Fermi-level pinning, 2) \rmMoO_\itx capping for doping, passivation and anti-reflection, and 3) a clean, non-damaging direct transfer method to realize devices on lightweight flexible polyimide substrates. These lead to record PCE of 5.1% and record specific power of \rm4.4 W g-1 for flexible TMD (\rmWSe2) solar cells, the latter on par with prevailing thin-film solar technologies cadmium telluride, copper indium gallium selenide, amorphous silicon and III-Vs. We further project that TMD solar cells could achieve specific power up to \rm46 W g-1, creating unprecedented opportunities in a broad range of industries from aerospace to wearable and implantable electronics.