ABSTRACT
Polycrystalline CuIn2Se3.5, CuIn2Se5 and CuIn5Se8 have been synthesized in vacuum. It is found that the presence of Cu-vacancies results in considerable deviation from the chalcopyrite structure of CuInSe2 The existence of a hitherto unknown β-phase, other than thiogallate, has been found for each of the three compositions by Rietveld refinement of XRD data, Electron diffraction and Photoluminescence measurements. The band gap of these compounds lie between 1.18 and 1.30 eV.
