Ultrathin Cu(In, Ga)Se2 solar cells

Within the UltraCIS project we have started to explore the possibility of reducing down the thickness of the Cu(In, Ga)Se₂ (CIGSe) layer to the sub-micron level (0.1μm) while maintaining a high efficiency level of solar cells. The three main approaches we used are: - Reducing the CIGSe thickness by chemical etching combining the thickness reduction and smoothing effect of the absorber. Efficiency higher than 10 % on small area cells with an absorber thickness of 0.5 μm are obtained. Losses were attributed exclusively to the reduced photocurrent and the loss on texturation of the absorber - Optical management by front contact texturation or by replacement of the back contact by the “lift-off” of CIGSe layer from the Mo layer and deposition of a new reflective back contact. - Application of plasmonic structures to CIGSe solar cells enabling light confinement at the subwavelength scale.