• Saraswat, Krishna C.
• Nitta, Frederick U.
• Hamtaei, Sarallah
• Brammertz, Guy
• Blackburn, Jeffrey L.
• Pop, Eric
• Daus, Alwin
• Hadermann, Joke
• Carr, Joshua M.
• Rahimisheikh, Sepideh
• Vermang, Bart
• Nassiri Nazif, Koosha
• Neilson, Kathryn M.
• Reid, Obadiah G.

Abstract

Semiconducting transition metal dichalcogenides (TMDs) are promising for high-specific-power photovoltaics due to their desirable band gaps, high absorption coefficients, and ideally dangling-bond-free surfaces. Despite their potential, the majority of TMD solar cells to date are fabricated in a nonscalable fashion, with exfoliated materials, due to the lack of high-quality, large-area, multilayer TMDs. Here, we present the scalable, thickness-tunable synthesis of multilayer WSe2 films by selenizing prepatterned tungsten with either solid-source selenium at 900 °C or H2Se precursors at 650 °C. Both methods yield photovoltaic-grade, wafer-scale WSe2 films with a layered van der Waals structure and superior characteristics, including charge carrier lifetimes up to 144 ns, over 14* higher than those of any other large-area TMD films previously demonstrated. Simulations show that such carrier lifetimes correspond to 22% power conversion efficiency and 64 W g-1 specific power in a packaged solar cell, or 3 W g-1 in a fully packaged solar module. The results of this study could facilitate the mass production of high-efficiency multilayer WSe2 solar cells at low cost.

Topics

• surface
• simulation
• layered
• tungsten
• power conversion efficiency