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Novel heterocyclic dyes were synthesized by attaching different electron-rich aromatics to the pyrrolo[2,3-b]pyrrole system by microwave irradiation system provided with condensation unit. The final push-pull conjugated dyes were yielded by azo coupling of PPY with aniline, 1-naphthylamine and N,N-dimethylaniline. Thin films of compound 3 have been chosen and prepared using thermal evaporation technique and investigated by FTIR and UV – VIS – NIR spectroscopy. Annealing out of PPY films at relatively low temperature ( ≤ 100 ​°C) for 3–6 ​min has been proved to notably reduce the energy gap and enhance both absorption and refractive indices. They manifested a fast response and high sensitivity toward iodine vapor with a low recovery time indicating a reversibility of iodine adsorption process.

Mn-doped MoO3 with different compositions in powder and thin film form have been prepared. The Orthorhombic (α-MoO3) crystal structure of pure MoO3 was revealed for (Mn)x(MoO3)1-x powdered samples, while the as-deposited films manifested an amorphous structure. FTIR spectra ensured that bonds are belonging to the vibrations of Mo O bonds to Mo–O–Mo stretching vibrations at the optimum peaks, confirming the presence of a single phase of MoO3. For powdered samples, the intensity of reflection has reached the maximum value (up to ≈ 85%) for (Mn)x(MoO3)1-x sample with x = 0.02 at.%, whereas the minimum value of reflection was obtained for undoped and (Mn)x(MoO3)1-x sample with x = 0.10 at.%. For thin films, the intensity of reflectance varies from 10% to 25% for all the samples. The optical energy was found to vary from 3.20 eV to 3.33 eV for the powdered samples and from 3.11 to 3.66 for as-deposited thin films. The photocatalytic properties were studied for all powdered samples by determining the absorbance of Methylene blue, using UV source as a function of illumination time. The degradation efficiency had maximum value of 48.5% at x = 0.10 at.%. The electrical conductivity study exhibited that, the maximum electrical conductivity of 3.11 × 102 (Ω m)−1 was obtained for the sample x = 0.10 at.%. It was a good match with the high degradation efficiency, minimum value of absorption, and narrow bandgap that existed due to the formation of the intermediate state of Mn.

Comparison of the absorption spectra of the ethanolic solution (3 ppm) of some diethyl 3,4-diaminothieno[2,3-b]thiophene-2,5-dicarboxylate (TT amino ester) derivatives has revealed that the azo dye derivative compound 4 manifests smaller band gap and higher absorption maximum close to solar maximum wavelength. Very good adhesive thin films to glass substrates of the azo dye compound 4 have been successfully prepared by thermal evaporation technique. The optical spectral analysis of such compound film revealed three absorption transitions corresponding to the optical gap, the electron transition between impurity levels in band gap and the fundamental band gap (HOMO to LUMO π→π* transitions). Absorption, dielectric and dispersion parameters have been determined for as- deposited and gas treated films and discussed. This film manifested a fast response and high sensitivity toward iodine vapor with a reasonable recovery time indicating a reversibility of iodine adsorption process. In contrast, the film illustrated slow response and weak sensitivity toward HCl gas with irreversible adsorption process. Besides, the azo dye compound 4 solution manifests strong emissive properties that recommend it as promising candidate for fluorescence sensors.

Co substitution in hexaferrites Sr1−xCoxFe12O19 compounds with doping values x = 0.0, 0.075, 0.15, 0.225 and 0.30 were prepared using microwave digestion system. Structural, morphological, magnetic and dialectic properties were investigated. X-ray diffraction pattern proved a hexagonal phase (SrFe12O19) existing as a main phase for all samples. The lattice parameters, crystallites size and other parameters such as microstrain and direct cell volume and dislocation density were calculated from the Rietveld refinement of the X-ray results. The SEM and TEM results confirmed a hexagonal structure existing. The histogram of the particle size distribution showed variation of the grain size with nano range between 90 nm and 178 nm. Magnetic results showed that the magnetization (M), saturation magnetization (Ms), and remnant magnetization (Mr) increased with increasing of Co substitution while the coercive magnetic field, Hc, fluctuated with increase of Co substitution because of the irregular change of the grain size of the samples. The sample x = 0.15 has a low coercive field because of the uniformity of the crystal grains. Such magnetic properties recommend this sample to be used in magnetic applications. The dielectric study of these samples revealed that the AC conductivity, σ, increases with increasing the frequency while impedance (Z), dielectric constant (e), dielectric loss, and tan δ decrease exponentially with F(Hz). The dissipation factor was found to have a convert frequency point at low F(Hz) after its starting to decrease slowly to the end of F-range. These dielectric properties suggest the validity of these hexaferrites compounds to be used as a capacitor.

The structural and electrical properties of the as-prepared and annealed In45Sb35Se20−xTex thin films with different compositions (x = 2.5, 5, 7.5, 10, 12.5 and 15 at.%) prepared by electron beam evaporation method are studied. The XRD patterns of the as-prepared thin film show that the investigated compositions have amorphous and polycrystalline structure depending on the Te content. After annealing the In35Sb45Se20−xTex thin films, at 473 K for 10 min, crystalline peaks are obtained. The electrical measurements were taken during heating in the range from 300 to 600 K. It was found that the resistivity decreases with increasing temperature for all the compositions indicating that these films have a semiconducting behavior. After annealing it was found that the room temperature resistivity of the investigated films were found depend on annealing temperature which cause a reduction by five orders of magnitude. These can be attributed to the amorphous–crystalline transformation, which is accompanied by a pronounced change in the electronic structure.

Polycrystalline solid solutions of (Bi1 − x Sb x )2Se3 (x = 0, 0.025, 0.050, 0.075, 0.100) were prepared using a facile method based on the conventional melting technique followed by annealing process. X-ray analysis and Raman spectroscopical measurements revealed formation of Bi2Se3 in single phase. The electrical and thermoelectric properties have been studied on the bulk samples in the temperature range 100–420 K. The electrical conductivity measurements show that the activation energy and room-temperature electrical conductivity dependences on the Sb content respectively exhibit minimum and maximum values at x = 0.05. The thermoelectric power exhibited a maximum value near the room temperature suggesting promising materials for room-temperature applications. The highest power factor value was found to be 13.53 μW K−2 cm−1 and recorded for the x = 0.05 compound.

Physical properties of In 35 Sb 45 Se 20− x Te x thin films with different compositions ( x =2.5, 5, 7.5, 10, 12.5 and 15 at %) prepared by electron beam evaporation method are studied. X-ray diffraction results indicate that the as-evaporated films depend on the Te content and the crystallized compounds consist mainly of Sb 2 Se 3 with small amount of Sb 2 SeTe 2 . Transmittance and reflectance of the films are found to be thickness dependent. Optical-absorption data indicate that the absorption mechanism is direct transition. Optical band gap values decrease with increase in Te content as well as with increase in film thickness.

The optical and electrical properties of the as-prepared and annealed Sn x Sb 20 Se (where x = 8, 10, 12, 13.5, 15, 16.5 and 18 at.%) thin films were studied. X-ray diffraction showed that all the as-prepared Sn-Sb-Se films were amorphous. Annealing the films at 473 K or above crystallized the films and the degree of crystallinity depended on the Sn content. The optical transmittance and reflectance were measured in the wavelength rang 200–2500 nm. The estimated optical band gap was found to decrease with increasing Sn content. A great difference in the optical constants values due to transformation from amorphous to crystalline phase structure of the films were found after annealing. This is advantageous for optical disk data storage applications. It was found that the resistivity decreases with increasing temperature for all the compositions indicating that these films have a semiconducting behavior with thermally activated conduction. The conduction in these films was suggested to be thermally assisted charge carrier movement in the extended states. Annealing the films caused a reduction in the room temperature resistivity by six order of magnitude. This was ascribed to the amorphous-crystalline transformation.

SnxSb20Se80−x chalcogenide alloys (with x = 8, 10, 12, 13.5, 15, 16.5 and 18 at.%) were prepared by the melt quenching technique. The average coordination number and the overall mean bonding energy were calculated. The x-ray diffraction studies revealed that the alloys with x = 8 and 10 at.% were amorphous and the alloy with x = 12 at.% was partially crystalline whereas the alloys with x = 13.5, 15, 16.5 and 18 at.% were crystalline. The glass transition temperature, the crystallization temperature, the melting temperature and the glass-forming tendency of the amorphous samples were determined from the differential scanning calorimetry measurements. The glass transition activation energies and the crystallization activation energies were determined using Kissinger as well as Augis and Bennett methods. Upon annealing the bulk amorphous samples at 573 K, two different crystalline phases, SnSe2 and Sb2Se3, were observed. X-ray reflectometry analysis revealed that the surface roughness increased with increasing annealing temperature. The density of the as-prepared films increased with increasing Sn content. Upon annealing at 523 K the density increased, whereas the density of most of the films decreased upon annealing at 573 K. Thermal gravimetric analysis showed a steeper weight loss upon heating after 533 K.

Polycrystalline single phase of Pb1−xSmxSe (x = 0.00–0.09) samples were prepared by the solid state reaction. XRD and SEM/EDAX methods were used for structural and chemical characterization of the obtained materials. The investigated samples were also characterized by the measurements of the samarium concentration dependence of the electrical conductivity and Seebeck coefficient. The power factor shows that these materials have the potential for high temperature applications with promising thermoelectric performance.

The effect of the In/Cd ratio on both the microstructure and the electrical conductivity parameters of CdS thin films, as a good material for optical windows, was investigated. A new preparation method of In-doped CdS films was used. The effects of annealing time and annealing temperature as well as of thin-film thickness on the mentioned physical properties were studied. Qualitatively, the increase of the In content with increasing In/Cd ratio could be observed using energy dispersive analysis of X-ray (EDAX), a matter which may be used to confirm the validity of the preparation method. The annealing process was found to promote the conductivity of the investigated thin films. This can be attributed to a crystallization process as revealed by X-ray diffraction patterns and scanning electron microscope photomicrographs.

Cadmium sulphide (CdS) thin films have been grown on corning glass substrate by thermal evaporation technique under base pressure 2 × 105 mbar. In this study we investigate the influence of Cadmium chloride (CdCl2) heat treatment and argon and oxygen (Ar + O2) annealing on the structural, morphological optical and electrical properties of CdS thin films to achieve high quality thin films for solar cells applications. X-ray diffraction (XRD), Field Emission scanning electron microscope (FE-SEM) and UV–Vis-NIR spectrophotometer were used to confirm and investigate the different physical properties of CdS films. The quality of CdS thin films crystallinity including the average grain size (D avg), the average lattice strain (e ls) and the dislocation density (ρ D) were extracted via XRD line broadening analysis. XRD analysis revealed that the samples are polycrystalline in nature with a mixed (hexagonal + cubic) structure and the crystallinity of the films increases with both (Ar + O2) annealing and CdCl2 heat treatment. After (Ar + O2) annealing and CdCl2 heat treatment processes the mean values of the grain size indicating the grain growth of CdS films. The surface morphology of the CdS films was examined by (FE-SEM) analysis; which confirmed the nano-crystalline nature of the CdS films with uniform coverage of the substrate surface; The optical properties of as-deposited, (Ar + O2) annealed and CdCl2 treated CdS films were discussed in detail. The optical energy gap was calculated using Tauc plot extrapolation. It was found to be increased from 2.43 eV for as-deposited film to 2.45 for CdCl2 treated CdS film. Swanepoel method was employed to estimate the thicknesses and extract the refractive index of the CdS films. The Room temperature resistivity decreased from 13.4 Ω cm for as-deposited CdS film to 2 and 0.8 Ω cm for (Ar + O2) annealed and CdCl2 treated CdS films respectively. The CdCl2 treated CdS film has the highest figure of merit value of 29 × 10−4 Ω−1. The obtained results confirm that the CdCl2 heat treatment process in (Ar + O2) atmosphere can enhance the physical properties of CdS thin films as a promising window layer or buffer layer material for CdS/CdTe and Cu(In,Ga)Se2 solar cells.

The crystallization kinetics, electrical and optical properties of as-prepared and annealed Ge x Sb 40-x Se 60 (22.5 at% < x < 32.5 at%) chalcogenide system have been studied. The kinetic studies using differential scanning calorimetry technique and X-ray diffraction examinations revealed that all the considered glasses can be crystallized to Sb 2 Se 3 and GeSe 2 phases. Electrical conductivity measurements elucidated that the Ge x Sb 40-x Se 60 amorphous thin films behave as semiconductor materials especially when the temperature of measurement exceeds a certain value which depends slightly on composition. The absorption coefficient-photon energy dependence of the investigated thin films could be described by the Tauc equation. The effect of high annealing temperature on both, the activation energy of the electrical conduction and the electronic energy gap have been reported and discussed.

Optical properties of amorphous Ge x Sb 40 − x Se 60 ( x =22.5, 25, 27.5, 30 and 32.5 at.%) thin films prepared by electron beam evaporation have been measured in the visible and near-infrared spectral region. The variations of the electronic energy gap ( E g ) with composition are discussed on the basis of both the overall mean bond energy and the topological model based on the structural dimensionality considerations. A pronounced peculiarity (maximum or minimum) appeared at around the same value of the average coordination number ( Z )=2.65 for all the compositional dependencies of electronic energy gap, high frequency dielectric constant, optical relaxation time and the dispersion parameters, is attributed to a topological phase transition from two-dimensional (2D) layer type to three-dimensional (3D) cross-linked network structures in the present glassy thin films. This confirms the suitability of structural topological model to explain the compositional dependencies of the physical parameters, not only for bulk glasses but also for thin films evaporated from them. These results are supported by volumetric and the calorimetric measurements.

Effects of Sb doping, sintering temperature and precoating with oxides on the optical and electrical properties of Sb-Sn-O thin films ~100 nm thick deposited by electron beam from bulk samples prepared using a sintering technique are investigated and discussed. All films have partially amorphous structure. The quality of the films as transparent-conductive ones has been examined using the so-called factor of merit. It was found to be a maximum for a film with Sb/Sn = 0.10 and enhanced by precoating with SiO2 as well as annealing. The lowest resistivity of about 3.65 ? 10-3 C m and transmittance of ~83.6% were attained for the unprecoated film after annealing for 5 h at 550 ?C.

Undoped and Sb-doped SnO2 films ∼100 nm thick have been deposited by electron beam evaporation from bulk samples prepared using sintering technique. Either undoped or Sb-doped SnO2 films are nearly amorphous, resistive and transparent. With increasing Sb content, the resistivity slightly decreases and then increases with further addition of Sb, which acts as donor and/or acceptor impurity atom in the SnO2 lattice, respectively. Besides, the doping of Sb inside the SnO2 lattice was associated with the increase in the film transmission at solar maximum wavelength and the width of optical band gap; which were interpreted in terms of the interaction between the two oxidation states of antimony, Sb3+ and Sb5+ and the increase of atomic bond energy, respectively. Moreover, the addition of Sb to the SnO2 lattice has proved to affect significantly on the refractive index, the extinction coefficient, concentration of free carriers, dielectric constant, electric carrier susceptibility and Mott's parameters, which have been explained and correlated to the film microstructure change.

Effects of annealing and film thickness on the electrical and optical properties of Sb:SnO 2 films deposited by electron beam from bulk samples prepared using sintering technique have been investigated. A compromise between low resistivity and high transparency of the film has been studied using the factor of merit. This factor, which has been found maximum for film 100 nm thick annealed at 550 °C for 15 min, seemed to be enhanced with increasing annealing time and/or film thickness confirming the simultaneous improvements of transparency and conductance with the latters. Other optical and electrical parameters such as refractive index, width of energy gap, density of localized states, concentration and mobility of carriers and Seebeck coefficient have been studied also, discussed and correlated to the microstructure changes with annealing and film thickness.

The electrical resistivity, π, and Seebeck coefficient,S, of the system Sb2Se3 were measured in the ambient temperature range 323≤T≤573 K. Both parameters were found to be affected considerably by the temperature of annealing,Ta, in the range 493≤Ta≤653 K and by the time of annealing,ta, for periods extending to 16h. Additionally, both depended strongly on the ambient temperature.

Some optical parameters of as-deposited and annealed GeSe 0.5 Te 3.5 thin films were studied in the visible spectral range using both absorbance and transmittance measurements. The heat treatment of the films proved that the variations of these optical parameters can be interpreted as a consequence of the internal microstructural changes caused by annealing. The increase of the optical gap with both annealing and increasing Se-Te ratio was explained in terms of diminution of disorder and defects in the structural bonding.

Some optical parameters of Bi2Te2Se thin films, determined from the measured absorbance and transmittance at normal incidence in the visible spectral range, were studied as functions of film thickness and annealing temperature. These parameters were found to be sensitive to both film thickness and microstructure change caused by annealing in a film. The effect of thickness and temperature of annealing on the optical gap was interpreted in terms of elimination of defects and change of disordering in the amorphous matrix.

We investigate the effects of the ambient temperature (T), both temperature (Ta)and time (ta)of annealing on the electrical conductivity (σ), and the Seebeck coefficient (S) of Sb2Te3. We concluded that both holes and electrons can participate to the conduction process. The material behaves as a semimetal. Although the Seebeck coefficient possesses a plus sign, the coefficient of S vs. \(\frac{1}{T}\) plots was negative as a degenerate semiconductor. The decrease in value of S with increasing tawas attributed to a corresponding decrease in the amount of positional disorder which acts as an electron trap center.

The thermal diffusivities, specific heats and thermal conductivities of the binary compositions Sb40Te60 and Sb40Se60 and the ternary composition Sb40Te30Se30 were measured in the range ∼320 to 500 K. It was found that the environmental temperature, the content of Se in the composition and the conditions of measurements are decisive factors greatly influencing both the values and the behaviour ot the thermal parameters, and the mechanisms of thermal transport. Although the tested compositions exhibit semiconducting behaviour, the free charge carrier component of the thermal conductivity was so small as to be negligible. Thus, it could be concluded that the observed thermal conductivity is attributable to both photon and phonon mechanisms.

Polycrystalline samples of (Bi0.95Sb0.05)2Se3 were prepared using the conventional melting technique at 1273 K, followed by annealing at different temperatures (423, 473, 523 and 573 K) for different time intervals (4, 8, 12 and 16 h). The samples were crystallized in a single phase of Bi2Se3 and no other phases or impurities were observed. The electrical and thermoelectric properties were studied by measuring the electrical conductivity and Seebeck coefficient as functions of temperature in the range 100–400 K. The results exhibited a metal–n-type semiconductor transition for all samples. The power factor (Pf) was calculated to determine the effect of the annealing treatment on the performance of the prepared material as a thermoelectric power generator. The highest room temperature value of the Pf was 6.9 μWK−2cm−1 and was recorded for the sample annealed at 573 K for 16 h. The results confirm the feasibility of using the annealing process to improve the performance of thermoelectric materials.