AbstractCu2ZnSnSe4 (CZTSe) is one of the promising materials as absorber layers in thin film solar cells. It contains earth abundant and non‐toxic elements. With a broad optical band gap at 1.5 eV as well as a high absorbance coefficient of 10–4 cm–1, CZTS is also a good light harvesting material. The aim of this study is to investigate the synthesis of kesterite rich CZTSSe using hot injection method in oleylamine. The material properties such as crystallinity, stoichiometry, and absorbance were studied depending on the synthesis and post‐treatment conditions by thin‐film X‐ray diffraction (XRD), energy, dispersive X‐ray spectroscopy (EDS) and UV‐Vis absorption spectra. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)