A new type of solar cell may one day prove so inexpensive and flexible, it could be used to turn your clothes into portable power sources—keeping you warm or cool, or charging your phone. Materials scientist Paul Alivisatos and colleagues at the University of California, Berkeley, mixed P3HT, a plastic that conducts electricity, with nanorods made from cadmium selenide, a semiconductor material. This mixture was then "spin-cast" onto a glass base, a process similar to swirling a wineglass so that the wine spreads into a thin film.