1. Fabrication of Flexible Photovoltaic Cells

Etching of Indium Tin Oxide (ITO) is an important step in the realization of organic photovoltaic cells. In the case of a glass substrate, the etching is carried out by hiding the areas that are to be preserved by varnish, then the samples are put in hydrochloric acid HCl, after that the samples will be cleaned in alcohols baths: acetone, ethanol and isopropanol. In the case of flexible substrates, the use of acetone to remove the varnish damages the plastic substrate. The solution to remedy this degradation is to use new technic which is photolithography. Flexible solar cells are made. The transparent electrode consists of ITO deposited on polyethylene terephthalate (PET). The active layer is composed on poly (3-hexylthiophene-2,5-diyl) (P3HT) and methyl ester of butyric acid [6,6]-phenyl C₆₁ (PCBM). Poly (3,4-ethylenedioxythiophene)-polystyrene sulfonate of aluminum. The structure of the final device is: PET/ITO/PEDOT:PSS/P3HT:PCBM/Al. the results obtained show that photolithography etching is an efficient technic for determining the geometry of the electrodes without causing damage to the plastic substrates.