A facile route for the synthesis of wurtzite Cu2ZnSnS4 (CZTS) nanocrystals was developed by an arrested precipitation method at 240 degrees C under simple reaction conditions with diethanolamine as the solvent and thiourea as sulfur source. The structure and morphology of the CZTS nanocrystals were characterized by X-ray diffraction and transmission electron microscopy. Control experiments demonstrated that CZTS nanocrystals which are purely wurtzite structure are readily obtained. The average diameter of the bulk CZTS products is found to be 10 +/- 1.1 nm. The estimated direct bandgap energy is 1.56 eV, which indicates that the CZTS nanocrystals produced by this method possess promising applications in photovoltaic devices. (c) 2012 Elsevier Ltd. All rights reserved.