Recent developments at Alta Devices have made clear the importance of paying very close attention to light management within solar cells. Our approach has pushed the world record for single-junction solar cells under a non-concentrated AM1.5G spectrum from its previous value of 26.4% to its current value of 28.8%. This has been enabled by our epitaxial lift off (ELO) process, which allows us to choose the precise thickness of the semiconductor stack, as well as to optimize the reflectivity of the back contact. This has allowed us to demonstrate extremely low dark currents, leading to a recent result with open-circuit voltage Voc of 1.126 V, previously unheard of with a GaAs absorber material.
Brendan Kayes is a member of the device group at Alta Devices, a startup company developing a high-efficiency, flexible, thin-film PV product. Alta Devices currently holds the world record for conversion efficiency of a single-junction device in non-concentrated sunlight, at 28.8%. Brendan received his PhD. from the California Institute of Technology, where he worked on silicon nanostructures for low-cost photovoltaics.