"Conventional solar cells need a secondary device, such as a battery, to store the electrical power generated from light. The photocapacitor combines the photoelectric and storage functions in a single structure.
The Japanese device consists of two electrodes -- a light-absorbing photoelectrode made of semiconducting titanium dioxide and a counterelectrode made of platinum coated glass -- separated by a resin film. Both electrodes include a porous layer of activated carbon that has a large surface area. All three layers are filled with an ionic solution and form a capacitor that has a light collection area of 0.64 square centimetres.
Photons are collected by photoreceptor dye molecules on the surface of the titanium dioxide layer. When exposed to light, electrons from the dye molecules are transferred to the conducting band in the titanium dioxide layer, thus producing a current. They then transfer to the activated carbon layer at the counterelectrode via an external circuit."
http://www.primidi.com/2004/11/05.html
http://physicsweb.org/articles/news/8/11/3/1
