Subnanoparticles
(SNPs) exhibit unique properties and functions
due to their extremely small particle sizes which extend into the
quantum scale. Although the synthesis of SNPs requiring precise control
of atomicity and composition has not been accomplished, we recently
developed an atom-hybridization method (AHM) that realizes such atomic-level
control using a macromolecular template. As a next step in the quest
for innovative quantum materials, the practical creation of functional
subnanomaterials will become a central subject. In this study, we
established a new screening technique for functional SNPs by focusing
on the simple indium–tin binary system with sequential compositions
using the latest AHM. As a result, it was revealed that a thermodynamically
unstable indium species was produced only at a certain composition
leading to a durable luminescent function. Such a phenomenon in subnanosized
substances will play an important role in the development of the as-yet-unknown
field of quantum materials.