Cu-Substituted Sb₂S₃ Nanopowders-Structural, Microstructural and Optical Analyses

Cu(I)-doped Sb₂S₃ powders were synthesized using the hot-injection method, with the aim of reducing crystalline particle size and tailoring their morphology to make them more spherical and better suited for spray deposition as an absorber layer in photovoltaic devices. Structural and microstructural analyses confirmed the successful formation of elongated (rod-like) crystalline Sb₂S₃ particles. CuSbS₂, itself a semiconducting material with a high light-absorption coefficient, formed in large amounts in Cu-doped systems, in the form of agglomerates of platelet-like particles. The third abundant phase was an amorphous phase present as spherical nanoparticles composed of uniformly distributed Sb, Cu and S. The presence of Cu decreased Sb₂S₃ particle size but did not significantly influence its morphology. Chlorides in the synthesis solution enabled faster crystallization than when acetates are the only present anionic species. When Cu, Sb and S sources were added during hot injection in stoichiometric amounts to form CuSbS₂, this phase was not reached, and Cu₉S₅ and Cu₁₂Sb₄S₁₃ were the dominant phases, indicating Cu-rich phases have a higher tendency to crystallize in specific conditions with an excess of antimony, and, potentially, sulfur is needed to obtain pure CuSbS₂.