In this study, we determine the refractive index (n), extinction coefficient (k), absorption coefficient (α) and optical band gap (E_g) of thin films based on the commercially available azo polymer (poly [1-[4-(3-carboxy-4-hydroxyphenylazo) benzene-sulfonamido]-1,2-ethanediyl, sodium salt]), usually denoted as PAZO, doped with InP/ZnS quantum dots (QDs) at concentrations of 1 wt.%, 2 wt.%, and 10 wt.%. It was found that the absorption of the composite materials studied is driven by direct allowed electronic transitions, with the band gap energies tunable from 2.92 eV to 3.00 eV depending on the dopant concentration. Furthermore, the results suggest that resonance energy transfer (RET) between the InP/ZnS quantum dots and the azo polymer may occur, actively modulating the optical properties of the composite materials in the 385–750 nm spectral region, where the PAZO absorption spectrum and the emission spectrum of the QDs overlap. The theoretical calculation carried out demonstrate that the energy transfer is more efficient at 600 nm, than at 420 nm, where the two observed peaks in the emission spectrum of the dopant are positioned. We believe that the result obtained may be of interest to researchers working on improving the photoresponse of azo polymers through incorporation of quantum dots, particularly given that most studies in this field focus on cadmium-containing nanocrystals, whereas InP/ZnS quantum dots represent a more environmentally friendly alternative.

New bulk chalcogenides from the system (GeTe₆)_1−xCu_x, where x = 5, 10, 15 and 20 mol%, have been synthesized. The structure and composition of the materials were studied using X-ray powder diffraction (XRD) and energy-dispersive spectroscopy (EDS). Scanning electron microscopy (SEM) was applied to analyze the surface morphology of the samples. Some thermal characteristics such as the glass transition, crystallization and melting temperature and some physico-chemical properties such as the density, compactness and molar and free volumes were also determined. The XRD patterns show sharp diffraction peaks, indicating that the synthesized new bulk materials are crystalline. The following four crystal phases were determined: Te, Cu, CuTe and Cu₂GeTe₃. The results from the EDS confirmed the presence of Ge, Te and Cu in the bulk samples in concentrations in good correspondence with those theoretically determined. A layered thin-film material based on Ge₁₄Te₈₁Cu₅, which exhibits lower network compactness compared to the other synthesized new chalcogenides, and the azo polymer PAZO was fabricated, and the kinetics of the photoinduced birefringence at 444 nm was measured. The results indicated an increase in the maximal induced birefringence for the layered structure in comparison to the non-doped azo polymer film.

New bulk chalcogenides from the system (GeTe6)1-xCux, where x=5, 10, 15 и 20 mol %, has been synthesized. The structure and composition of the materials was studied using X-ray powder diffraction (XRD) and energy dispersive spectroscopy (EDS). Scanning electron microscopy (SEM) has been applied to analyze the surface morphology of the samples. Some thermal characteristics as glass transition, crystallization and melting temperature and some physicochemical properties as density, compactness, molar and free volume were also determined. The XRD pattern shows sharp diffraction peaks indicating that the synthesized new bulk materials are crystalline. The following four crystal phases were determined: Te, Cu, CuTe и Cu2GeTe3. The results from the EDS confirm the presence of Ge, Te and Cu in the bulk samples in a concentration in good correspondence with those theoretically determined. A layered thin film material based on the synthesized new Ge14Te81Cu5 chalcogenide, which has the most flexible structure, and the azo polymer PAZO has been fabricated, and the kinetic of the photoinduced birefringence at 444 nm has been measured. The results indicate an increase in the maximal induced birefringence for the layered structure in comparison to the non-doped azo polymer film.

Bulk chalcogenides from the system (GeTe₄)_1−xIn_x, where x = 0; 5 and 10 mol%, were synthesized by a two-step melt quenching technique. New layered composite materials based on them and the azo polymer [1-4-(3-carboxy-4-hydrophenylazo) benzensulfonamido]-1,2-ethanediyl, sodium salt] has been prepared through spin coating, electrospray deposition and via vacuum-thermal evaporation of the chalcogenide and spin coating of the azo polymer onto it. Using the latter technology, a material consisting of one chalcogenide and one azo polymer film and three chalcogenide and three azo polymer films has been fabricated. The carried-out SEM analysis shows that in the materials, initially prepared as a bilayer and multilayer structure, diffusion at the chalcogenide/polymer interface occurs leading to the formation of a homogenous composite environment. Birefringence was induced at 444 nm in all the fabricated thin film materials. The highest value of the maximal induced birefringence has been measured for the material fabricated as a stack, Δn_max = 0.118. For the material prepared as a bilayer structure and the composite material obtained through electrospray deposition, the maximal induced birefringence takes values of Δn_max = 0.101 and Δn_max = 0.095, respectively. The sample prepared via spin coating of the chalcogenide/PAZO dispersion has the lowest value of the maximal induced birefringence (Δn_max = 0.066) in comparison to the pure PAZO polymer film (Δn_max = 0.083).