In this recent work, we showed a new design of mechanically flexible and optically semitransparent solar cells with high efficiency. The ultrathin geometry of the microcell together with the neutral plane design enabled the solar cells could be bent to a radius as small as 4.9 mm (the size of a pencil). The position of the silicon neutral plane was given analytically, which provides a criterion for the geometry optimization. The strain in the silicon was shown to be much smaller than the failure strain by both theoretical analysis and finite element simulations. User-definable transparency feature was also obtained by utilization of optical concentrator and sparse layout of microcells. The mechanical flexibility and optical transparency imply it's broad applications on clothes, buildings and cars.  This work was featured on the cover of November, 2008 issue of Nature Materials.

The full paper could be found at:  http://www.nature.com/nmat/journal/v7/n11/abs/nmat2287.html