First-principles studies of vibrations in photovoltaic material Cu2ZnSnSe4

Chalcopyrite-type CuInSe2 (CIS) has received attention as one of the most promising materials for thin film solar cells. It is found that Cu2ZnSnSe4 (CZTSe) and Cu2ZnSnS4 (CZTS) emerged as promising candidates for solar cell applications. These new quaternary materials exist in various modifications, namely stannite (ST) and kesterite (KS).On the basis of density functional calculations of electronic structure by the SIESTA method in the local density approximation, the zone-center vibrational spectra for two crystallographic modifications of Cu2ZnSnSe4 (CZTSe) are constructed. The difference of frequencies, between kesterite and stannite phases, of some characteristic modes is discussed. It is suggested to use some of these modes (notably the Zn-related one at 239–254 cm-1) as a vibrational signature of the kesterite structure, e.g., for samples characterization

Keywords:

photovoltaic , semiconductors , phonon , vibration spectra