Concentration dependence of As₂S₃ chalcogenide glass cluster size in amine solution

Solution processing chalcogenide glasses is a common and effective first step in optoelectronic device fabrication. Arsenic(iii) sulfide (As₂S₃) is believed to take on a nanoscale cluster structure in n-propylamine and n-butylamine, which affects the morphology and properties of the deposited material; however, the size of these clusters and the mechanism of size determination are poorly understood. We combine experimental and analytical techniques to investigate As₂S₃ cluster size in n-propylamine and its dependence on solution concentration. We find that the cluster size increases with concentration and show that this trend is consistent across independent experimental techniques. We then explain these results by proposing a simplified dissolution mechanism and deriving cluster size through a free energy argument. Our findings enable informed control of chalcogenide glass cluster size during solution processing and improved property control in optoelectronic device fabrication.