Analysis of Atomic and Electronic Structures of Cu2ZnSnS4 Based on First-Principle Calculation

Atomic and electronic structures of Cu2ZnSnS4 (CZTS) are discussed on the basis of the first-principle pseudopotential method. CZTS is usually assumed to have the stannite or kesterite structure, but one can consider three other structures under the condition that a S atom is bonded to two Cu, one Zn, and one Sri atom. For each of the five structures, the lattice constants and atom positions are optimized, and the total energy and density of states are calculated. The energy difference per atom between the structures is smaller than the thermal energy at room temperature, and therefore, CZTS is expected to be composed of five phases with different crystal structures. X-ray diffraction patterns simulated on the basis of the calculation results are consistent with the experimental results. (C) 2009 The Japan Society of Applied Physics