High-efficiency transition metal dichalcogenide solar cell fabrication

Stanford researchers in the Pop Lab in conjunction with IMEC, Belgium developed a scalable, mass-production-friendly process method for high-quality, multilayer transition metal dichalcogenide (TMDs) films based on selenization/sulfurization of transition metals/metal oxides. Due to their desirable band gaps and high absorption coefficient, TMDs are promising for next generation, high specific power solar cells. Current TMD fabrication methods rely on exfoliating small flakes from a bulk TMD crystal, which does not produce full, mass production friendly, multi-layer films.

The Pop Lab deposited wafer-scale, multilayer tungsten diselenide (WSe₂) films by selenizing pre-deposited, pre-patterned tungsten with solid source selenium and H2Se precursors (See Fig. 1). These WSe2 films yield a charge carrier lifetime of up to 144 ns, corresponding to power conversion efficiency of ~22% and specific power of ~64 W g-1 in a packaged solar cell, and ~3 W g-1 in a fully packaged solar module. Initial focus was WSe₂, but the method could be applied to sulfur (instead of selenium), and other transition metals or even other transition metal oxides (e.g. WSe₂, WS₂, MoSe₂, MoS₂). This breakthrough could pave the way for mass-production of low cost, high-efficiency, lightweight, flexible, multilayer WSe2 (and other TMD) solar cells that are capable of irregular shapes like a drone wing, car roof, or wearable devices. Alternatively, layered TMDs could be used as contact layers for CdTe and CIGS solar cells.

Stage of Development - Prototype