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The 220-billion-dollar Internet of Things (IoT) market is growing rapidly. IoT wireless devices are soon scaling to trillions of units, which entails the use of energy harvesting solutions due to the maintenance and environmental issues associated with batteries. A lightweight, flexible solar cell could seamlessly power or charge IoT devices both indoors and outdoors. For successful adoption, such a solar cell needs to be eco-friendly and bio-compatible, and reliably provide high power-per-weight (specific power) at low cost. Modern solar cell technologies miss at least one of these criteria.
Emerging transition metal dichalcogenides (TMDs) are promising candidates for flexible high-specific-power photovoltaics due to their excellent optical and electrical properties. 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. In this talk, I explain how we addressed these fundamental issues and as a result achieved record efficiency of 7.5% and record specific power of 6.5 W g−1 in flexible TMD (WSe2) solar cells, the latter on par with established thin-film solar cell technologies. We further project that future TMD solar cells on thinner substrates and with higher efficiency can achieve an additional 10x increase in specific power, opening unprecedented opportunities in IoT and beyond.
Koosha received his Ph.D. (2022) in Electrical Engineering and M.S. (2016) in Mechanical Engineering from Stanford, and B.S. (2014) in Mechanical Engineering from Sharif University of Technology. Along the way, he did internships at Apple (OLED/LCD displays) and HP Labs (3D Electronics). He is now a postdoctoral scholar at Pop Lab at Stanford developing novel flexible sensors and solar cells for use in IoT devices, wearable electronics, electric vehicles, and unmanned aerial vehicles.
