  Studies of photoluminescence (PL) can provide fundamental insight into the
optical properties of semiconductor nanoparticles (NPs) but the same is being
limited by NP size distribution and low luminescence yield. Inorganic
semiconductor core/shell structures have added advantage of durability, high
luminescence quantum yield (LQY), 10-80% in the visible range and useful in
biological labeling, LED and luminescence thermometry application. However,
luminescence thermometry requires narrow PL line width, intense luminescence
and should change with temperature linearly and reversibly which are difficult
to achieve from lattice mismatched (3.9%-10.6%) core/shell structures. Here, we
report a lattice matched, durable and very small (2.8nm) HgTe/CdTe core/shell
NPs whose optical activities are shown to be in the UV range and have yielded
very high luminescence. The reversible change of PL with temperature of the
core/shell NPs is used as an optical probe temperature sensor with resolution
0.32% per degree Kelvin which deemed to be one of the efficient luminescence
thermometers reported till date.
