X-ray absorption spectroscopic study of photovoltaic solar cell materials of the type A^IB^IIIC₂^VI with special reference to CuInSe₂

Abstract

The K absorption discontinuity of copper has been recorded for compounds of the type A^IB^IIIC₂^VI using a Cauchois-type bent crystal X-ray spectrograph. The chemical shift in the positions of the discontinuity in the compounds relative to that in pure copper metal is found to be governed by the effective charge on the copper ion. A linear relationship between the chemical shifts and the band gaps has also been observed. This dependence is useful in determining the values of the band gaps in materials for which they are not known. It is shown that an approximate picture of the band structure of CuInSe₂ can be obtained from X-ray absorption near-edge structure studies.