High-Quality Semiconductor Nanocrystals through Eutectic Processing

The use of eutectic reactions in colloidal semiconductor nanocrystal (NC) synthesis has recently opened a route to materials with exceptional structural and optical quality. Unlike conventional hot-injection and ripening methods, eutectic-like NC-halide mixtures can promote thermodynamically driven shape evolution through transient, halide-induced recrystallization of semiconductor nanoparticles. This mechanism has proven remarkably versatile, producing a broad range of metal chalcogenide NCs, including alloys and core/shell heterostructures with reduced defect densities and improved photostability. Despite these advances, the chemical pathways governing eutectic-like reconstruction in NCs remain poorly understood, leaving the field in an early stage of development. This Perspective examines the evolving picture of NC growth through halide-induced reconstruction, highlights representative examples of shape and line width control, and discusses the emerging theoretical insights into the underlying mechanisms. We further review evolving applications of eutectic processing in NC light-emitting devices, optical gain media, photovoltaics, and scintillators. Finally, we discuss future opportunities for the field, including broader adoption of eutectic conditions as a general synthetic strategy for colloidal nanomaterials, its extension to challenging compositions such as III-V semiconductors, and eutectic processing of NC films to create epitaxially connected nanoparticle assemblies.