CuIn < inf > 1-x < /inf > Al < inf > x < /inf > Se < inf > 2 < /inf > solar cells fabricated on the flexible substrates by co-sputtering and modified selenization

Abstract

CuIn1-xAlxSe2 (CIAS) thin films were grown on the flexible stainless steel substrates, by dc co-sputtering from the elemental cathodes. CuInAl alloyed precursor films were selenized both by noble gas assisted Se vapor transport and vacuum evaporation of Se. X-ray diffraction, scanning electron microscopy and UV-visible absorption spectroscopy were used to characterize the selenized films. The composition (x=Al/Al+In) with 0≤x≤0.65 was varied by substituting Al with indium in CuInSe2. Lattice parameters, average crystallite sizes and compact density of the films compared to CuInSe2, decreased and (112) peak shifted to higher Bragg's angle, with Al incorporation. Cells were fabricated with the device structure SS/Mo/CIAS/CdS/iZno-AZO/Al. Best cell showed the efficiency of 6.8%, with x=0.13, Eg=1.17 eV, fill factor 45.04, short circuit current density Jsc 30 mA/cm2. © 2013 IEEE.