The potential to produce ultraviolet (UV) light-emitting
devices
has attracted significant interest in interdisciplinary fields, particularly
in the use of 0D halide nanostructures due to their straightforward
synthesis methods and exceptional efficiency in optoelectronics. Here,
we present a systematic study involving nanostructure synthesis and
significant changes in the electronic structure caused by finite-size
effects. We have focused on the investigation of size effects on the
UV-light emitting properties of all-inorganic Cs3Cu2I5 halide. We observe that bulk particles present
a pronounced bright-blue emission at 440 nm with a high quantum yield
of 80%. Very small quantum dots nanostructures (6–10 nm) reveal
a significant shift of the photoluminescence peak down to ∼395
nm, close to the UV-A region, but with a quantum yield reduction of
10%. Surface engineering to obtain very small nanoparticles free from
defects at the nanocrystal surface is crucial for maintaining a high
quantum efficiency, allowing their use in UV-emitting devices.