Nanocomposites and nanomaterials
The waveguide structures based on CdTe/CdS quantum dots– polymer layer-by-layer films on optically active Ti/TiO2 substrates. 
Tynkevych O.O., Gerasymov R.Y., Khalavka Y.B.
Department of General Chemistry and Chemistry of Materials, 
Yuriy Fedkovych Chernivtsi National University. 
Kotsiubynsky Str. 2, 58012, Chernivtsi, Ukraine
E-mail: y.khalavka@chnu.edu.ua 
Multistage anodization of titanium plates allows the obtaining of highly ordered TiO2 nanoporous surface, varying in pore diameter and porosity. The structural morphology of TiO2 nanoporous arrays depends on the anodization parameters and electrolyte compositions [1]. On the other hand, it is known that one-stage short-term anodization leads to the growth of the TiO2 colored anodic films [2].
The main purpose of presented work was to evaluate the anodization conditions that led to controlled growth of TiO2 layers of well-defined colours and evaluate the possibility of using them as a substrate for the waveguide structures based on CdTe/CdS quantum dots (QDs).
The conditions of controlled anodization of titanium plates with the usage of an aqueous electrolyte of orthophosphate acid (weight 20%) at a temperature of 45°С and direct voltage equal to 20 V have been established, which allows us to obtain an optically active in the visible light range of TiO2 layer on the titanium plate surface. The increase of anodization time (1, 5 and 10 min) changes the color of anodized titanium plates from red to violet and blue by the formation of TiO2 layer on the plate surface. The optically active substrates of Ti/TiO2 allows to vary the photoluminescence intensity of waveguide structures based on CdTe/CdS QDs – polymer layer-by-layer films. The used CdTe/CdS QDs have a maximum photoluminescence peak at 650 nm.
The violet and blue colored Ti/TiO2 substrate leads to the quenching of CdTe/CdS QDs photoluminescence intensity. The red colored Ti/TiO2 substrate can be used to enhance the light-guiding efficiency for the photoluminescence of CdTe/CdS QDs.
1.	Kapusta-Kołodziej J., Tynkevych O., Pawlik A., Jarosz M., Mech J., Sulka G. D. Electrochemical growth of porous titanium dioxide in a glycerol-based electrolyte at different temperatures // Electrochimica Acta.- 2014.- 144.- P. 127-135.
2.	Delplancke J. L., Degrez M., Fontana A., Winand R. Self-colour anodizing of titanium // Surface Technology.- 1982.- 16(2).- P. 153-162.