Selenization of metallic Cu-In thin films for CuInSe2 solar cells

Abstract

A new approach for formation of photovoltaic CuInSe₂ films by chalcogenization of Cu‐In multilayers with a thin selenium layer and subsequent heat treatments is presented. Morphological, compositional, and structural properties of films along with aspects of various processing conditions are discussed. The possibility of obtaining perfectly homogeneous chalcopyrite ternary films was affected by composition deviations from stoichiometry, although films obtained in a modified two‐stage heat treatment processing were of good structural and photovoltaic quality. Heterojunctions with (Zn, Cd)S as window material showed efficiencies better than 5%, mainly limited by low open‐circuit voltage and poor fill factor. Short‐circuit currents were comparable to CuInSe₂‐based cells fabricated by multiple‐source evaporation.