Synthesis and characterization of kesterite Cu2ZnSnTe4 via ball-milling of elemental powder precursors

A homologous series of kesterite light absorber materials Cu2ZnSnX4 (CZTX; X: S, Se, Te) can be used for realization of multi-junction solar cells. A stable member of the series (i.e. Cu2ZnSnTe4 (CZTTe)) was synthesized using a mechano-chemical route from its elemental precursors. Detailed characterization of the as synthesized as well as annealed CZTTe samples are being reported. XRD, Raman, TEM and SEM-EDS studies as well as Raman spectra confirm the formation of single-phase, stoichiometric, kesterite CZTTe nano-crystalline powder. The bandgaps of various samples of CZTTe were found in the range of 0.84-0.88 eV as confirmed by UV-Vis-NIR spectroscopy. The low band gap < 1 eV, coupled with the high absorption coefficient of similar to 10(4) cm(-1) suggests the possible use of this material as the absorber layer in the bottom cell of all kesterite multi-junction solar cells