12.8% efficiency Cu(In, Ga)Se-2 solar cell on a flexible polymer sheet

A lift-off process has been developed to obtain Cu(In,Ga)Se-2 solar cells o n flexible polymer sheets. The absorber layer is grown by a co-evaporation method on a polyimide layer, which is spin coated on a NaCl covered glass s ubstrate. The NaCl inter mediate layer can provide Na to the Cu(In,Ga)Se-2 layer during deposition. After the complete processing of the cells, the Na Cl buffer layer is dissolved to separate the glass substrate from the ZnO/C dS/Cu(In,Ga)Se-2/Mo/polyimide stack. A record conversion efficiency of 12.8 % (total area) under AM1.5 illumination was indendently measured at EhG/ISE , Freiburg, Germany. Such high efficiency solar cells on light weight and f lexible substrates are needed for novel terrestrial and space applications. Copyright (C) 1999 John Wiley & Sons, Ltd.