Single-phase and well-dispersed Cu1.75S nanocrystals by ambient pressure diethylene glycol solution synthesis

► Single-phase, well-dispersed Cu1.75S nanocrystals were synthesized by diethylene glycol based solution process. ► Influence of hydrazine, ethylenediamine additions and synthetic temperature on nanocrystals growth was investigated. ► Flaky-shaped Cu1.75S nanocrystals with narrow size distribution were obtained at refluxing temperature 200 °C and above. ► The DEG solvent phase synthesis is a green, cheap and facile route to prepare Cu1.75S nanocrystals.