To fabricate solar cells outside, without the ultra-sophisticated techniques of preparation of materials semidrivers? Mean, told themselves four Danish researchers and German who introduce their method in the magazine Nanotechnology. A method which is almost recovering from the kitchen, since it leans on a mixture of nanoparticles of oxide of zinc and of a polymer which, heated in 210°C, gives a solar cell ready for job.

Today, the photovoltaic production of the cells of trade leans on technologies of electronic industry. On the material semidriver, most often some silicon, are engraved the circuits which will produce current when the sun is informed. Methods which are played under space and that request “white rooms”, air of which is ultra-filtered to eliminate dusts.

Frederik Krebs and his colleagues of the technical University of Denmark and of the university of Fribourg (Germany) chose another way. They finely blended in a liquid solution of the particles of oxide of 3,5-nanometre zinc (1) and a soluble polymer, before heating the whole. A stage which was outside made, in their laboratory, without being concerned about the temperature and about the rate of humidity. This film is then put between an électrode of money in the back, and on the front a film of oxide of indium-tin deposited on a plastic or glass substrate, bought at an industrialist (2). In short an element in four layers fabricated in some minutes!

Of course, side performance, it is not this. Tested in calibrated artificial lighting, output is only 0,1 %, two - five times less than other cells fabricated in the atmosphere controlled by a box with glove. On the other hand, the cell loses only 20 % of its effectiveness in time, what is not much compared with other plastic solar cells. But so that their present cell an interest other than pedagogic, the researchers have a lot to do. In Germany, scientists of the institute Fraunhofer of the energy systems have just established a new record of Europe, with a 39,7 % got output by concentrating the sun 300 times, opening perspectives for one power station solar energies photovoltaic to concentration. But there, it is heavy physics with cells based on germanium and of iodure of gallium doped in the phosphorus and in the arsenic. Under space this time.

(1) Millionth 3,5 of millimetre

(2) These substrates are delicate to fabricate, from technology of deposition in stage steam

Picture: © Denis Delbecq