CUINS2 THIN-FILM FORMATION ON A CU TAPE SUBSTRATE FOR PHOTOVOLTAIC APPLICATIONS

A new technique, ''CISCuT'', for the preparation of polycrystalline si ngle-phase CuInS2 thin films for solar applications has been developed . In a continuous roll-to-roll process a copper tape is at first elect rochemically plated with an In layer. This tape undergoes in a second step at about 600 degrees C a rapid sulfurization process at atmospher ic pressure. Structural and electrical characterization (XRD, SEM, TEM , EDXS, I/V-characteristics) reveals that in this high-speed, highly p roductive process photoactive CuInS2 is formed. Single-phase CIS films of about 1.5 mu m thickness, consisting of grains with 1-2 mu m later al dimensions are grown. The present state of understanding of the CuI nS2 formation is discussed in some detail. First solar cells prepared from this material show efficiencies around 6%. The new experimental a pproach described here is promising to become an effective low-cost me thod for the production of thin-film CIS absorber layers without any v acuum step. The continuous growth process from roll to roll is possibl y a way to make solar cell and modul production competetive with conve ntional energy generation. (C) 1998 Elsevier Science B.V. All rights r eserved.