Over 10 g of non-stoichiometric Cu2ZnSnSe4 colloidal nanocrystals for thermoelectric applications are prepared after one single reaction. The obtained pellet made from the colloidal nanocrystals shows a peak ZT value of 0.44 at 450 degrees C, which is similar to those of state-of-the- art Cu2ZnSnSe4-based bulk materials at the same temperature.