One‐Step Solvothermal Synthesis of Cu(In, Ga)Se ₂ Powders: Effects of Synthesis Parameters on Phase Evolution and Morphology

Cu(In, Ga)Se ₂ (CIGS)‐based chalcopyrite powders are promising precursor materials for thin‐film photovoltaic applications, but many low‐cost solution‐based synthesis methods require substantial amounts of complexing agents. In this study, CIGS powders were synthesized by a one‐step solvothermal route using triethanolamine (TEA), while the precursor‐to‐solvent ratio was adjusted to reduce TEA use relative to precursor loading and control phase development. The effects of reaction temperature (180–240 °C) and time (10–40 h) on phase evolution and morphology were systematically investigated. X‐ray diffraction (XRD) revealed increasingly pronounced chalcopyrite‐related reflections with temperature and reaction time, although contributions from secondary phases could not be excluded. Scanning electron microscopy (SEM) showed substantial changes in particle morphology and agglomeration. Within the investigated conditions, powders synthesized at 200 °C exhibited favorable chalcopyrite‐related phase development and morphological evolution, whereas prolonged treatment at 240 °C produced greater structural and morphological complexity. Further optimization at 240 °C demonstrated that the precursor‐to‐solvent ratio influenced phase development and particle morphology. Energy‐dispersive X‐ray spectroscopy (EDS) confirmed Cu, In, Ga, and Se in the analyzed region. The selected powder synthesized at 240 °C for 20 h with doubled TEA and fourfold precursor loading exhibited a BET specific surface area of 27 m ² g ⁻¹ , supporting subsequent powder‐processing studies.