Investigation of vulcanization of non-crystalline Cu2ZnSnS4 nano-particles

• Non-crystalline Cu2ZnSnS4 (CZTS) nano-particles were synthesized.
• After vulcanizing, the CZTS films showed some voids and grain size of 500 nm.
• Cu3SnS4 was obtained when the vulcanization temperature exceeded 500 °C.
• Pure Kesterite CZTS was obtained at a vulcanization temperature as low as 400 °C.

Non-crystalline Cu2ZnSnS4(CZTS) nano-particles were fabricated by hydrothermal method. CZTS nano-particles that have different Cu/(Zn + Sn) ratio (0.77, 0.89, 1.02) were separately prepared. The morphology, composition and crystal structure of the as-prepared nano-particles and the vulcanized films were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractometry, and Raman spectroscopy. When the temperature and time of vulcanization exceeded 400 °C and 60 min, respectively, the Cu-rich phase (Cu3SnS4) emerged. Sn lost during vulcanization. CZTS sample with 0.77 Cu content (Cu/(Zn + Sn) = 0.77) showed pure kesterite CZTS without secondary phases when they were vulcanized at 400 °C for 60 min.