Nanooptics and photonics
Spectral and nonlinear optical charachterization of CdTe/CdS quantum dots in polymer film
Multian V.V.1, Uklein A.V.1, Okrepka G.2, Vorontsov D.3, Khalavka Yu.3, Pokutnyi S.I.4, Gayvoronsky V.Ya.1
1 Institute of Physics, NAS of Ukraine, 46 Nauky pr., Kyiv 03028, Ukraine
E-mail: vlad@iop.kiev.ua
2 Bukovinian state medical university, 2, Theatralna sq., Chernivtsi, 58012, Ukraine
3 Institute of Biology, Chemistry and Bioresources, Yuriy Fedkovych Chernivtsi National University, 2 Kotsjubynskyi St., Chernivtsi, 58012, Ukraine.
4 Chuіko Institute of Surface Chemistry, NAS of Ukraine, 17 General Naumov Str., Kyiv 03164, Ukraine
Last time the quantum dots (QDs), are used in many different fields: solar batteries and concentrators for them; lasers, as materials for diodes, displays of monitors and smartphones. Thin polymer films with incorporated QDs are new materials and can be used in the most of the above applications. Polymer PDDA films with core/shell CdTe/CdS QDs were obtained by layer-by-layer technique [1]. Three series of composites with incorporated CdTe/CdS QDs of different radii were obtained: for “green” 1.3nm, for “orange” 1.55nm and for “red” 1.75nm that were encoded due to their color of photoluminescence.
Theoretical analysis has revealed the mechanism of the QDs photoluminescence. It was shown that the oscillator’s strength and the dipole moment of the transition have high magnitudes [2] vs. the corresponding ones for bulk semiconductors. Analysis of the experimental elastic optical scattering angular distribution has shown a rise of the intrinsic optical absorption cross-section σabs ~ V3 within core/shell CdTe/CdS QDs size enlargement. The films with the QDs demonstrate an efficient refractive |Re(χ(3))| ~ 10-5 esu and absorptive |Im(χ(3))| ~  10-8 esu nonlinear optical responses at 532 nm within pulsed laser excitation. The nonlinear optical responses efficiencies crucially depend on the QDs size. [3] The applied optical diagnostics techniques can be used for nondestructive express analysis of new nonlinear optical materials and composites.
1.	Doskaliuk N., Khalavka Y., Fochuk P. Influence of the shell thickness and ratio between core elements on photostability of the CdTe/CdS core/shell quantum dots embedded in a polymer matrix, NRL -2016, -11, 216.
2.	Pokutnyi S. On an exciton with a spatially separated electron and hole in quasi-zero-dimensional semiconductor nanosystems. Semiconductors -2013, -47, 791.
3.	Multian V., Uklein A., Lisnyak V., Gayvoronsky V. et al. Synthesis, characterization, luminescent and nonlinear optical responses of nanosized ZnO. NRL -2017, -12, 164