The original goal of our study is to synthesize by co-evaporation the phase that could be formed at the interface between polycrystalline p-Cu(In,Ga)Se2 treated with KF and n-CdS. Hence, a new buffer layer, CdIn2S4 (C24), deposited by co-evaporation is presented for the use in thin film solar cells, exhibiting device efficiencies as high as 16.2%, comparable to that obtained on a reference standard CdS-buffered device. The physico-chemical and optical properties of close to stoichiometry 400 nm-thick films of C24 show similar properties to what has been reported in the literature for single crystals. The layer stack used for solar cells is investigated by transmission electron microscopy, showing the formation of an ultrathin Cd-deficient C24 layer at the CIGSe/C24 interface, while a clear lattice match is observed at the C24/ZnO interface. Advanced electrical characterizations of the devices suggest that the output voltage and fill factor of the solar cells based on Cu(In,Ga)Se2/(PVD)C24 are limited by tunneling-enhanced recombination through extended band tail states. These results open new routes to explain the superiority of wet processes used for the junction formation compared to vacuum-based approaches.

$Cu_{2}O{\backslash}ZnO$ nanowires (NWs) heterojunctions were successfully prepared by combining Atomic layer Deposition (ALD) and Electrochemical Deposition (ECD) processes. The crystallinity, morphology and photoconductivity properties of the$Cu_{2}O{\backslash}ZnO$ nanostructures have been investigated. The properties of the $Cu_{2}O$ absorber layer and the nanostructured heterojunction were studied in order to understand the mechanisms lying behind the low photoconductivity measured. It has been found that the interface state defects and the high resistivity of $Cu_{2}O$ film were limiting the photovoltaic properties of the prepared devices. The understanding presented in this work is expected to enable the optimization of solar cell devices based on $Cu_{2}O{\backslash}ZnO$ nanomaterials and improve their overall performance.

In this study, we have used RF-magnetron sputtering to deposit Al-doped ZnO (AZO) nanostructures thin films on poly-ethylene naphthalate (PEN) substrates. The compacted AZO nanopowders with different Al concentrations (0, 1, 2, 3 and 4 at.%), which were synthesized by sol–gel method combined with a supercritical drying process, have been used as targets. Structural, optical and electrical properties of deposited thin films with different Al concentrations have been investigated. X-ray diffraction results indicated that all the deposited thin films have hexagonal wurzite structure with c-axis orientation without any secondary phases. The SEM cross section image of the films revealed very dense columnar nanostructure. The best electrical properties (ρ = 4 × 10−4 Ω cm, µ = 22 cm2 V−1 s−1, and ne = 8 × 1E20 cm−3) were obtained for the AZO samples containing 2 at.% of Al. The thin films show an average transmittance of 80 % with the PEN substrate in the visible region.

Titanium dioxide (TiO2) thin films were deposited on glass substrates by spray pyrolysis technique from different solution volumes. We studied the effect of sprayed solution volume on the structural, morphological and optical properties of TiO2 films. X-ray diffraction studies revealed the presence of an anatase phase with a tetragonal structure with (101) preferred orientation. The best crystallinity was obtained in the case of a sprayed solution volume of 60 ml. Also, this film had a lower average surface roughness (RMS) as measured by atomic force microscopy. Transmission and reflection optical analysis showed interference phenomena indicating a smooth reflecting surface of the film. An indirect band gap of about 3.46 eV was found, indicating a potential use of these films in solar cell devices. Based on the optical measurements, the film thickness was determined by the envelope method, which was in agreement with the scanning electron microscopy result. Wemple–Di Domenico single oscillator and Spitzer–Fan models were used to study the optical constants of the films grown from different sprayed solution volumes. Photoluminescence emission intensity was found to increase with increasing film crystallinity, and the spectra showed ultraviolet and visible emissions corresponding to intrinsic emission and trap levels within the band gap, respectively.

High quality Cu2ZnSnS4 (CZTS) thin films, as an absorber layer for thin films solar cell, were synthesized successfully using a simple and low cost technique, Close-Space Vapor Transport (CSVT). The films were grown on soda-lime glass substrates using a polycrystalline CZTS ingot as source of evaporation material. Influence of substrate temperature on chemical composition, morphological, structural, electrical and optical properties of the CZTS thin films was investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, UV-Vis-NIR spectrophotometer, Hall effect and photoluminescence (PL) measurements. The results from XRD and Raman characterization confirmed the formation of kesterite CZTS thin films with a (112) plane preferred orientation and Raman shift of 338 cm-1, respectively. When the substrate temperature was increased from 460 to 540 °C, the composition of the thin films becomes Cu-, Sn-poor and Zn-rich, wherein the optical band gap values increased from 1.34 to 1.52 eV. PL spectra show the presence of broad emission band at 1.28 eV. All CZTS thin films exhibit p-type conductivity. With substrate temperature of 500 °C, the CZTS thin films show the best properties as an absorber layer in thin film solar cell (Eg = 1.48 eV, p = 3.4 x1017 cm-3, ρ = 2.6 Ω/cm, μ = 6.4 cm/V.s).

Phonon dispersion ω(q) and phonon density of states g(ω) of the high-pressure rocksalt phase of InN are calculated ab initio, at different pressures, using the density functional perturbation theory. Born effective charge e ∗ T , LDA values of dielectric con- stant ∞ and of the electronic gap E g are obtained as well. Building on the theoretical knowledge of phonon frequencies and their evolution with pressure, we attempt to interpret the set of six bands found previously in Raman spectra of epitaxial layers and of InN-nanowires.

Nanostructured Zn1−xVxO (0 ⩽ x ⩽ 0.50) thin films were synthesized by rf-magnetron sputtering at two different substrate temperatures (room temperature (RT) and 200 °C) and with variable sputtering powers (60, 80 and 100 W). In this method, single targets based on Zn1−xVxO nanopowders prepared by the sol–gel process were used. Characterization of the Zn1−xVxO nanoparticles showed that they crystallize in the hexagonal wurtzite structure. Their size ranged from 20 to 40 nm. The effect of process parameters on the physical and chemical properties of Zn1−xVxO thin films has been studied. For x ⩽ 0.30, the results obtained at 200 °C and 60 W indicate that the films have a high quality of crystallinity. Vegard’s law is respected, indicating that vanadium is incorporated in the ZnO matrix. The chemical compositions of these films were found to be close to the stoichiometry. The films exhibit a columnar structure and a smooth surface. Their average transmission, from the visible to the NIR, was in the range of 75–90%. The values of the band gap of the Zn1−xVxO thin films with x ⩽ 0.30 and elaborated at 200 °C and 60 W, vary from 3.29 to 3.74 eV. This is consistent with blue shifting of near-band edge cathodoluminescence emission. Under particular growth conditions, the investigation shows that the Zn0.80V0.20O sample presents the best properties for potential use in various optoelectronic applications, namely: a single wurtzite phase, low surface roughness (Ra ∼ 0.2 nm), a high transparency of 90% in the UV–Vis–NIR, a wide band gap of 3.74 eV and a resistivity of ∼5 × 10+3 Ω cm.