Chemical Spray Pyrolysis (CSP) technique was utilized for depositing 'Extremely Thin Absorber (ETA)' layer solar cells having phases of both CuInS2 and Cu2S in the absorber, so as to have multiple band gaps of 1.45 eV and 1.80 eV respectively. Cell fabricated using this absorber is almost equivalent to a tandem cell capable of absorbing photons of two energies. This was achieved simply by lowering concentration of indium in conventional CuInS2. Presence of both CuInS2 and Cu2S phases were confirmed through X-ray diffraction and Raman studies. Multiple absorptions in the film were evident from the absorption spectra. Also the 'CuInS2:Cu2S' absorber was used for the fabrication of ETA solar cell with structure ITO/(CuInS2:Cu2S)/In2S3/Ag. Comparing with performance of ITO/CuInS2/In2S3/Ag solar cells, they exhibits 17%, 15% and 47% increases in short circuit current, fill factor and efficiency respectively. The best device realized in this study has open circuit voltage of 518 mV and short circuit current density of 14.25 mA/cm(2). Efficiency and fill factor were 3.82% and 52% respectively. (C) 2015 Elsevier Ltd. All rights reserved.