Electronic structure of stannite-type Cu2ZnSnSe4 by first principles calculations

The electronic structure of stannite-type Cu2ZnSnSe4 was studied by first-principles calculations. The valence and maximum (VBM) is an antibonding of Cu(3)d and Se 4p orbitals. The conduction band minimum (CBM) is an antibonding Sn 5s and Se 4p orbitals. The Zn atom does not affect lie VBM or the CBM in CZTSe. The Cu-Se is a weak covalent bonding because both occupied, and the bonding orbital of Cu 4s and Se 4p is occupied and the antibonding orbital is unoccupied. The band structure of CZTSe has a partially localized Sri 5s orbital. The electrons of Sri 5s do not greatly contribute to the chemical bonding because of an inert pair effect. The electronic structure of CZTSe is discussed in comparison with that of CuInSe2. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim