Japanese researchers have developed a novel solar cell that produces electricity from sunlight as normal but can also store this energy without the need for a battery. The new "photocapacitor" was designed by Tsutomu Miyasaka and Takurou Murakami at Toin University in Yokohama. It could revolutionize portable electronic devices, such as mobile phones and other hand-held devices, allowing users to charge up the device even on cloudy days. The photocapacitor uses a unique combination of materials. A light-absorbing photoelectrode made of titanium dioxide is kept separate from a platinum-coated glass counterelectrode by a resin film. Additionally, both electrodes include a porous carbon layer filled with electrolyte. The titanium dioxide generates the charge which is then stored by the electrolyte on the large surface area of the porous carbon.