Publication date: 15th May 2025
Ligand chemistry plays an important role in the synthesis, morphology, and resultant properties of colloidal nanomaterials. Synthetically, ligand stereoelectronics contribute significantly to the reactivity of both precursors and resultant crystal facets, mandating their judicious use. Carboxylates, amines, thiolates, and phosphonates stand out as the most employed ligands in the synthesis of III-V and II-VI semiconductor nanocrystals. Despite the strategic role phosphonates play in the morphology of II-VI materials like CdSe, their use in III-V materials such as InP is under-explored. In fact, there are no reports of InP quantum dots synthesized bottom-up from indium phosphonates. The two reports of this chemistry instead show the formation of a new species that forms between 300ºC and 370ºC, exhibiting a unique optical profile with peaks and linewidths consistent with a phosphonate-ligated InP nanocluster.The narrow and trap-free PL of these clusters stands in contrast to the commonly observed PL from native InP QDs, making them a promising system for realizing the outstanding challenge of synthesizing stable and blue-emissive InP nanocrystals. We illuminate the intimate relationships between synthetic conditions, surface chemistry, structure, and the photoluminescence behavior of these clusters using a combination of solid-state NMR, variable temperature and time-resolved photoluminescence, and synchrotron pair distribution function analysis. These data highlight the interplay between the speciation of surface ligands and observed photoluminescent properties, informing future strategies to tune cluster PL.