Abstrakt
The A2B6 quantum dots (QDs) are perspective, tunable and photostable luminophors for optoelectronic devices, especially for those, where light conversion is needed. However, such applications require embedding QDs into solid state composites resistant to temperature changes and protected from oxygen.
The most promising candidates for QDs incorporation are inorganic salts thanks to their matrix stability. Inorganic salt potassium dihydrogenphosphate (KDP) has unique non-linear optical properties that can be combined with properties of QDs.
Here we report on formation of single crystals of KDP doped by CdTe/CdS QDs, which were prepared by a slow evaporation technique from the mixture of saturated salt and colloidal solutions. The obtained crystals preserved optical properties of QDs and dramatically increased their chemo- and photostability.
We demonstrate application of such composites as infrared light conversion devices. The conversion is done via two-step process: from infrared light (1064 nm) to the second harmonic (532 nm), which is then transformed into the photoluminescence of QDs.
We found that emission spectra of QDs, as well as their photoluminescence lifetime are practically identical both under UV and IR light excitations. Moreover these composites are made from cheap and abundant elements, the obtained samples have broad excitation and emission range, and fast response time.
Since the composites "salt:QDs" have wider working thermal range then colloidal solutions themselves, the luminescent thermometry can be proposed as another possible application. Thus, the temperature dependence of photoluminescence of KDP:CdTe/CdS composites is discussed, as well.