Controlled Synthesis of Copper Indium Gallium Selenide Quantum Dots in Green Solvents via Hot‐Injection: Regulation of Structure and Optical Properties by Reaction Conditions and Gallium‐to‐Indium Ratio

Copper indium gallium selenide (CIGSe), a group I‐III‐VI semiconductor, holds broad application prospects in fields such as solar cells, light‐emitting diodes, photocatalysis, and photodetectors due to its excellent optoelectronic properties. Its bandgap can be flexibly tuned by adjusting the In/Ga ratio, enabling efficient absorption of the solar spectrum. In this study, environmentally friendly and safe CIGSe quantum dots (QDs) were successfully synthesized via the hot‐injection method in triethylene glycol (TEG). CIGSe QDs with good crystallinity were synthesized by varying reaction temperature and time, and the variation of the bandgap was investigated by changing the Ga/In ratio. The obtained QDs were characterized using techniques (X‐ray Diffraction (XRD), TEM, Energy dispersive spectroscopy (EDS), UV–vis, X‐ray photoelectron spectroscopy (XPS), and Raman). The results indicate that CIGSe QDs synthesized at 230°C for 10 min exhibit optimal crystallinity. Furthermore, at this temperature, the ligand desorption rate is moderate, preventing QD agglomeration. The average particle size is 5.21 nm with a bandgap of 2.00 eV. By adjusting the Ga/In ratio (0:1 ∼ 1:1), the bandgap can be tuned within a range of 1.84 ∼ 2.08 eV. This study provides a new approach for green and controllable synthesis of CIGSe QDs and lays a material foundation for future evaluation of their potential in optoelectronic devices.