For the synthesis of Zn-alloyed CIS NCs, indium acetate (0.1 mmol), copper (I) acetate (0.1 mmol),zinc acetate (0–0.5 mmol), DDT (2.0 mL), oleic acid (0.4 mL), and 6 mL of ODE were added into a 50 mL three-necked, round-bottom flask. The reaction solution was degassed under vacuum for 10 min at room temperature until no bubbles observed and then the
solution was heated to 140 C at a rate of 20 C/min under vacuum using a heating mantle. An argon atmosphere was introduced into the flask. The temperature of the solution was quickly raised to 230–260 C at a rate of 10 C/min. All other steps were same as in the preparation of Cd–CIS NCs.