ABSTRACT
The current state of the problem of nonstoichiometry in the I-III-VI2 compounds in the framework of statistical thermodynamics, atomic and band approaches is reviewed with emphasis on main achievements and problems. The original results on investigation of the I-III-VI2 homogeneity regions and interaction between intrinsic defects are presented. The most important tasks of further studies of nonstoichiometry in the I-III-VI2 phases are pointed out.
