South Korean scientists have created solar PV cells that are 1 micrometer thick, hundreds of times thinner than most PV and half again as thin as other kinds of thin-film PV. (The research is in a paper just published in Applied Physics Letters.)

The cells are made with gallium arsenide as the semiconductor, "cold welded" directly onto a metal substrate, with no adhesive to make them thicker. Remarkably, they produce roughly as much power as thicker PV cells, though in testing, "the cells could wrap around a radius as small as 1.4 millimeters."

With cells this thin, solar PV can be integrated in all sorts of "wearables" -- clothes, glasses, hats, or backpacks with solar cells integrated, continuously feeding power to our portable electronics. More to the point, PV could be integrated into just about anything.