Optical Properties Of Cu Research Articles

Optical Properties of Cu, Ni, and Co Nanoparticles Synthesized by Pulsed Laser in Liquid Ambient

Optical Properties of Cu, Ni, and Co Nanoparticles Synthesized by Pulsed Laser in Liquid Ambient

Influence of gamma radiation on structural, microstructural and optical properties of Cu$${}_{2}$$ZnSnS$${}_{4}$$ (CZTS) thin films prepared by thermal evaporation technique

Influence of gamma radiation on structural, microstructural and optical properties of Cu$${}_{2}$$ZnSnS$${}_{4}$$ (CZTS) thin films prepared by thermal evaporation technique

Luminescent Copper(I) Halides for Optoelectronic Applications

Lead‐free copper(I) halides have been demonstrated to exhibit high photoluminescence quantum yields with high air and light stability, making them one of the most promising semiconductors for next‐generation light‐emitting diode devices. The low‐dimensional structures and soft lattices of Cu(I) halides induce the formation of self‐trapped excitons (STEs) to achieve broadband emissions with high quantum yields. Herein, the recent studies on the electronic and optical properties of Cu(I) halides (i.e., Cs3Cu2X5, CsCu2X3, and A2CuX3, where A = K+ or Rb+, X = Cl−, Br−, or I−) are reviewed and particular emphasis is placed on the role of the dimensionality and the halide in governing the electronic and optical properties (e.g., emission color and photoluminescence efficiency) via STEs. Several optoelectronic applications of Cu(I) halides are also discussed. In the last section, perspectives and challenges for the future development of Cu(I) halides in both optoelectronic and photocatalytic applications are outlined.

Computational studies of the electronic structure of copper-doped ZnO quantum dots

Copper-doped ZnO quantum dots (QDs) have attracted substantial interest. The electronic structure and optical and magnetic properties of Cu3+(d8)-, Cu2+(d9)-, and Cu+(d10)-doped ZnO QDs with sizes up to 1.5 nm are investigated using the GGA+U approximation, with the +U corrections applied to d (Zn), p(O), and d(Cu) orbitals. Taking +Us parameters, as optimized in previous bulk calculations, we obtain the correct band structure of ZnO QDs. Both the description of electronic structure and thermodynamic charge state transitions of Cu in ZnO QDs agree with the results of bulk calculations due to the strong localization of Cu defect energy levels. Atomic displacements around Cu are induced by strong Jahn-Teller distortion and affect Kohn-Sham energies and thermodynamic transition levels. The average bond length of Cu-O and the defect structure are crucial factors influencing the electronic properties of Cu in ZnO QDs. The analysis of the optical properties of Cu in ZnO QDs is reported. The GGA+U results, compared with the available experimental data, support Dingle's model [Phys. Rev. Lett. 23, 579 (1969)], in which the structured green luminescence observed in bulk and nanocrystals originates from the [(Cu+, hole) → Cu2+] transition. We also examine the magnetic interaction between the copper pair for two charge states: 0 and +2, and four positions relative to the center of QDs. Ferromagnetic interaction between ions is obtained for every investigated configuration. The magnitude of ferromagnetism increases for positive charge defects due to the strong hybridization of the d(Cu) and p(O) states.

Influence of Annealing Methods on the Morphological and Optical Properties of Cu<sub>2</sub>O Nanoparticles Prepared by Chemical Bath Deposition

In this work, the cuprous oxide (Cu2O) thin film on glass substrates were fabricated at low growth temperature by a single-step aqueous solution of chemical bath deposition method. In order to optimize optical and morphology quality, the effect of two different heat treatment methods are conventional furnace annealing process and continuous wave (CW) CO2laser annealing technique were investigated. The effect of annealing temperatures on the properties of Cu2O thin films were systematically investigated by UV-Vis spectrophotometer, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

Structural, morphological and optical properties of Cu–Fe–Sn–S thin films prepared by electrodeposition at fixed applied potential

Cu–Fe–Sn–S films were obtained on indium tin oxide / glass substrates by a low-cost electrodeposition using an aqueous solution of CuSO4, FeSO4, SnSO4, and Na2S2O3 at room temperature followed by high-temperature sulfurization (500 °C) in argon flow. A range of cathodic potentials have been used for electrodeposition, those being chosen after a preliminary cyclic voltammetry study. The coatings were characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray Photoelectron Spectroscopy and conventional spectroscopy (diffuse reflectance and specular transmission). The results are discussed with respect to the used applied potential.

Structural evolution, optical properties, and photocatalytic performance of copper and tungsten heterostructure materials

Several studies reported that modifying CuO with CuWO4 can increase its photoactivity. In this study, copper and tungsten heterostructure materials were synthesized via a simple sol-gel method using ammonium paratungstate. The temperature’s influence (300, 500, 700, and 900 °C) was analyzed in the structural, morphological, microstructural, and optical properties of Cu and W materials using X-ray diffraction, infrared spectroscopy, field emission-scanning electron microcopy, transmission electron microscopy, diffuse reflectance spectroscopy, and dynamic light-scattering studies. The CuO diffraction patterns exhibited a tenorite phase formation, and the copper-tungsten materials diffractograms demonstrated the formation of CuO/CuWO4 at 300 and 500 °C and CuO/CuWO4/Cu2WO4/WO3 materials at 700 and 900 °C with crystallite sizes from 25 to 56 nm. Intense vibrational modes obtained at 300 °C for the CuWO4 phase decreased at 500 °C. Therefore, 500 °C is not a temperature that promotes CuO/CuWO4 heterostructure formation. Analyses conducted using microscopy techniques demonstrated the morphology of the CuO/CuWO4 heterostructure obtained at 300 °C, where CuWO4 nanoparticles covered the CuO polyhedral; microstructural analysis verified the heterostructure’s formation. The synthesized materials at 300 °C had an optical band gap of 2.66 eV (direct gap) and 1.35 eV and 2.11 eV (indirect gap), which were lower values than those of the CuO and CuWO4. The temperature at 300 °C proved to be optimal for the formation of the CuO/CuWO4 heterostructure. Only the material obtained at 300 °C exhibited a photocatalytic response in the rhodamine B degradation due to a possible interfacial charge transfer between the CuWO4 and CuO. The synthesis process used to obtain the CuO/CuWO4 heterostructure was novel, with a short processing time, low energy consumption and cost, and environmentally friendly properties.

Electron paramagnetic resonance and optical properties of Cu+2 in PbO-Li2O-As2O3-B2O3 glasses

The room temperature electron paramagnetic resonance (EPR) and optical absorption studies of PbO-Li2O-As2O3-B2O3 glasses have been done by introducing a transition metal ion Cu+2 ion as a spin probe with fixed mole% in the given glass composition. Glasses containing transition metal (TM) ion give the information of site symmetry around the Cu+2 ion of the host glass. The EPR spectra of Cu+2 in all glass samples recorded in the X-band frequency (9.1–9.7 GHz) have similar features. The spin-Hamiltonian parameters have been calculated; the observed values are g|| > g⊥ > ge and A|| > A⊥. It suggests that the site symmetry around Cu+2 ion is tetragonal distorted octahedral and the ground state of Cu+2 is dx2-y2 (2B1g) orbital. The Cu+2 ion is coordinated with six ligand atoms in a distorted octahedron site symmetry. The optical absorption spectra exhibit a broadband corresponding to d-d transition bonds of Cu+2 ion. Calculated bonding parameters suggest the covalent nature of in-plane σ-bonding (α2) and pure ionic nature for out-of-plane (β2) and in-plane π-bonding (β12). This data is correlated with the theoretical optical basicity (Λth) values, and it is observed that the Γσ value increases whereas Γπ values decrease with increasing Λth.

Enhanced Magnetic and Optoelectronic Properties of Cu-Doped ZnO: Mn Nanoparticles Synthesized by Solution Combustion Technique

Nano-ZnO and ZnO doped with Cu: Mn samples (Mn = 2% and Cu = 2% and 4%) have been synthesized by combustion synthesis. The effect of Cu content (Cu/Mn co-dopant) on the structural, optical, and magnetic properties has been studied. X-ray diffraction studies revealed hexagonal Wurtzite structure, and the particle size is around 36–18 nm. From scanning electron microscopy (SEM) analysis, morphology of all the samples was spherical in shape with high porous structure. The elemental composition of the synthesized samples was investigated using energy dispersive X-ray analysis (EDAX), which confirmed the presence of selective elements in the samples near stoichiometric ratio. FTIR spectra confirmed the presence of functional groups in synthesized samples. From UV–Vis absorbance spectra, blue shift is observed with increasing dopant concentration. From VSM studies, the enhanced magnetization properties were observed in doped samples. From photoluminescence (PL) studies, decrease in rate of recombination of electron–hole pairs is observed. The simultaneous enrichment of magnetic and optical properties of Cu doped ZnO: Mn nanoparticles can be used in future spintronic and optoelectronic devices.

Structural, morphological, electrical and optical properties of Cu doped DLC thin films

In this research, effect of copper (Cu) doping on the structural, optical, morphological and electrical characteristics of diamond like carbon (DLC) thin films have been investigated. Thin films of DLC and Cu doped DLC (Cu-DLC) have been deposited on glass substrates by pulsed Laser Deposition (PLD) technique. XRD results showed that at 1.5% of Cu doping, Cu form cluster in DLC. Below of this doping ratio, Cu has amorphous form in DLC. AFM reveals that the minimum surface roughness was observed for the 1.0% DLC thin film with the root mean square surface roughness (Rrms) of 2.07. The Rrms values for the 1.5%, 2.0% and 2.5% Cu-DLC thin films are 2.45, 3.14 and 3.89 respectively. The average sheet resistivity of films is decreased by increasing the Cu concentration, according to Four Point Probe technique.

Engineering the optical properties of Cu doped CeO2 NCs for application in white LED

Cerium dioxide (ceria, CeO2) with wide band gap (3.6 eV) is optically transparent for visible light and efficiently luminescent in the UV-range. Here, we have investigated the effect of Cu dopant ions on the structural and optical properties of Ce1-xCuxO2; (0.00 ≤ x ≤ 0.20) nanocrystals (NCs) synthesized via co-precipitation technique. XRD results confirmed the successful incorporation of Cu ions into CeO2 single-phase cubic system. The decrease in the crystallite sizes (13 - 4 nm) as the Cu content increase indicates towards the decrease in the crystal quality and introduction of additional lattice defects. The concentration of oxygen deficiency (δ) and the reduction in the oxygen valency (CeO2-δ) have been evaluated quantitatively using Raman spectroscopy. The possible defects, assessed via Photoluminescence (PL) emission spectra, generate profound energy bands localized in the forbidden band region, which causes a lowering in the UV emission efficiency and narrowing the band gap energy from 3.7 eV for pure CeO2 to 3.1 eV for 20% Cu doped sample. The green PL emission band at ~520 nm (2.39 eV) is attributed to electronic decay from conduction band (CB) to donor band of oxygen vacancy (Ov), while the blue band at ~ 420 nm (2.9 eV) is due to electronic transition from CB to accepter band formed by ceria vacancies (VCe2−). The values of chromaticity coordinates and illuminating engineering parameters such as color rendering index (CRI) and correlated color temperature (CCT) of the studied samples predict their possible use in white light-emitting diode (LED).

First principle investigation of hydrogen behavior in M doped Cu2O (M = Na, Li and Ti)

We study the hydrogen effect on the electronic, magnetic and optical properties of Cu$_2$O in presence of different dopants (Na, Li and Ti). The electronic properties calculations show that hydrogen changes the conductivity of Cu$_2$O from p to n-type. The results show that interstitial hydrogen atom prefers to locate in the tetrahedral site in Cu$_2$O system and it decreases the band gap value of the later. The Na or Li doping Cu$_2$O preserves the p-type conductivity of Cu$_2$O, while hydrogen is the source of n-type conductivity in Na or Li doped Cu$_2$O systems. Ti doping increases the band gap value of Cu$_2$O and makes it an n-type semiconductor. Hydrogen increases the optical transmittance of M doped Cu$_2$O.

Morphology and optical properties of Cu–Al co-doped ZnO nanostructures

We have synthesized Cu–Al co-doped ZnO nanostructures with two steps processes i.e. seed deposition by ultrasonic nebulizer 1.7 MHz and ZnO nanorods were grown by chemical bath deposition (CBD) at 95 °C for two hours. According to scanning electron microscopy (SEM) images, the ZnO nanostructures change from nanorods to square nano-disks when Cu increased, and Al maintained constant. X-ray diffraction (XRD) pattern confirm that the Cu–Al co-doped ZnO nanostructures have a polycrystalline hexagonal wurtzite structure. Optically, the reflectance (R%), the transmittance (T%), and an absorbance of ZnO nanostructures influenced by the morphology. Further investigation, a proper content of Cu doping generates strong absorption in the range of ultraviolet (UV) and visible wavelength. Meanwhile, by increasing Cu content, the band gap energy of ZnO nanostructures tend to increase and photoluminescence (PL) energy in the visible range has a maximum peak of 1.75 eV. We believed the existence of Cu and Al compositions cause modification and the defects distribution change in ZnO nanostructures.

Green luminescence and calculated optical properties of Cu ions in ZnO

There are two characteristic optical transitions associated with Cu ions in ZnO, the 0.72 eV infrared and the 2.86 eV structured green luminescence (SGL). While the former is unambiguously related with the d(Cu2+) intra-shell transition, there is no generally accepted mechanism of the SGL. Besides the original model of Dingle [Phys. Rev. Lett. 23, 579 (1969)], two other mechanisms were recently proposed. We report an analysis of the optical properties of Cu in ZnO by ab initio calculations. The GGA+U approach is used, with the +U corrections applied to d(Zn), p(O) and d(Cu) orbitals. The results, compared with the available experimental data, support the Dingle's model, in which the SGL originates in the (Cu1+, hole) → Cu2+ transition. A good agreement with experiment is obtained also for the internal transition at 0.72 eV. The absence of an expected radiative transition at about 2 eV is explained by its quasi-forbidden character.

X-ray photoelectron spectroscopy, Raman and photoluminescence studies on formation of defects in Cu:ZnO thin films and its role in nonlinear optical features

The structural, optical, morphological and nonlinear optical properties of Cu:ZnO spray-coated films are studied. The surface morphology of Cu:ZnO thin films turned out to be homogenous, crack free and well covered with pea-shaped grains. The peak shift observed in the x-ray photoelectron spectroscopy spectra of the Cu:ZnO thin films infers the defect states present in the films. The satellite peak observed at 939.9 eV for Cu2P core-level spectra confirms the +2 oxidation state of Cu in the films. The formation of additional defect levels in the nanostructures upon Cu doping was investigated using photoluminescence (PL) and Raman spectroscopy studies. The luminescent centers in the violet, blue and green spectral region were observed. The most prominent emission was centered at the blue color center for 5% Cu:ZnO thin films. The enhancement in the PL emission intensity confirms the increase in the defect state density upon Cu doping. The shifting of the UV emission peak to the visible region validates the increase in the non-radiative recombination process in the films upon doping. The phonon modes observed in Raman analysis around 439, 333 and 558 cm−1 confirm the improvement in the crystallinity and formation of defect states in the films. X-ray diffraction reveals that the deposited films are of single-phase wurtzite ZnO structure with preferential growth orientation parallel (0 0 2) to the C-axis. The third-order optical susceptibility χ(3) has been increased from 3.5 × 10−4 to 2.77 × 10−3 esu due to the enhancement of electronic transition to different defect levels formed in the films and through local heating effects arising due to continuous wave laser illumination. The enhanced third harmonic generation signal investigated using a Nd:YAG laser at 1064 nm and 8 ns pulse width shows the credibility of Cu:ZnO films in frequency tripling applications.

Optical Properties of Cu2ZnSn(SxSe1‐x)4 by First‐Principles Calculations

Structural, electronic, and optical properties of Cu2ZnSn(SxSe1‐x)4 semiconductors are studied theoretically for different concentration of S and Se anions. The optical properties are calculated at three levels of theory, in the generalized gradient approximation (GGA), meta‐GGA, and with a hybrid functional. The GGA and meta‐GGA calculations are corrected with an on‐site Coulomb Ud term. Lattice constants, dielectric constants, and band‐gaps are found to vary almost linearly with the concentration of S. The authors also show that a dense sampling of the Brillouin zone is required to accurately account for the shape of the dielectric function, which is hard to attain with hybrid functionals. This issue is resolved with a recently developed based interpolation scheme, which allows us to compare results of the hybrid functional calculations on an equal footing with the GGA and meta‐GGA results. We find that the hybrid functionals provide the overall best agreement with the experimental dielectric function.

Structural and optical properties of Cu–N codoped ZnO thin films deposited by magnetron cosputtering

ZnO films codoped by copper and nitrogen were prepared by magnetron cosputtering. The effects of this codoping on the structural and optical properties of ZnO films were systematically studied. The results show that Cu–N codoping didn’t affect the optimal orientation. Cu–N codoping can enlarge the grain size, enhance the crystallinity, reduce the stress and lead to denser and smoother surface. A significant red shift of absorption edge and gap-narrowing effect resulting from codoping were found in ZnO films. Cu-doping, N-doping, and oxygen vacancy are the main factors leading to property modification of the ZnO films. By Cu–N codoping, we can modulate the microstructure and optical properties of ZnO films in a wider range.

Study of the structure and optical properties of Cu and Mn in situ doped ZnS films by chemical bath deposition

The in situ doping of ZnS films with Cu and Mn ions was obtained by the chemical bath deposition method. The resulting films, with cubic crystalline structure, were specular, adherent, and optically transparent. The analysis from X-ray photoelectron spectroscopy confirmed the effective insertion of Cu and Mn ions and the formation of defects in the crystalline structure of the ZnS films. Moreover, the morphology analysis showed that the presence of the doping ions in the reaction solution promoted the deposition of films with better uniformity. The effects of the doping agents in the optical properties of the ZnS films were also analyzed. First of all, it was observed a red-shift of the optical absorption edge, and therefore, the decrease of the optical band gap. Afterwards, the room-temperature photoluminescence spectroscopy confirmed the effective activation of the ZnS film with Cu and Mn ions, when the luminescence emission centered at 470 nm was shifted to longer wavelengths (green-orange emissions centered at 530 nm). Based in these results, it is concluded that the process reported here could be used as an original alternative for the preparation of ZnS films with a mixture of other doping agents.

Structural and optical properties of Cu incorporated ZnFe2O4 ferrite nanoparticles prepared by wet chemical route

We report facile synthesis of Cu incorporated multifunctional ZnFe2O4 nanoparticles (Zn1-xCuxFe2O4) using simple wet chemical route. The as prepared samples having various Cu cation contents (x = 0 to 0.8) were calcined at 600 °C for 10 h. Samples of particular composition, x = 0.4 (Zn0·6Cu0·4Fe2O4) were calcined at different temperatures (200 °C to 800 °C) to study the effect of calcination on structural and optical properties. X-ray diffraction studies reveal the presence of mixed phases, i.e. normal cubic spinel ferrite and hematite structure (α-Fe2O3). Calcination of Zn0·6Cu0·4Fe2O4 shows further improvement in the crystallinity without segregation of any additional impurity phase. UV-Vis absorbance studies show CuO phase at longer wavelengths for high Cu cation content, while Raman spectral analysis shows the presence of prominent peaks at 220 cm−1, 287 cm−1, 400 cm−1, and relatively weak broad peak at 640 cm−1 corresponding to normal ferrite structure and α-Fe2O3 structure, confirming the X-ray results.

Electronic and optical performances of (Cu, N) codoped TiO2/g-C3N4 heterostructure photocatalyst: A spin-polarized DFT + U study

The geometrical, electronic and optical properties of Cu or/and N (co)doped TiO2/g-C3N4 heterostructure systems have been investigated systematically on the basis of spin-polarized density functional theory calculations. Our calculated results indicate that the band gap of TiO2/g-C3N4 heterostructure has an obvious narrowing compared with pure TiO2 (1 0 1) surface, and (Cu, N) codoping can induce some impurity states of N 2p and hybridized states of Cu 3d and N 2p appearing in the forbidden gap of TiO2/g-C3N4 heterostructure, which lead to a decrease of the photon excitation energy and an obvious redshift of the optical absorption edge. Moreover, the charge density difference calculations of Cu or/and N (co)doped TiO2/g-C3N4 heterostructure systems show that the excited electrons and holes will eventually accumulate in (co)doping TiO2 (1 0 1) surface and g-C3N4 monolayer, respectively, which can effectively reduce the recombination of the photogenerated electron-hole pairs by the interfacial coupling of between TiO2 (1 0 1) surface and g-C3N4 monolayer. This work not only investigates systematically the electronic and optical properties of Cu or/and N (co)doped TiO2/g-C3N4 heterostructure, but also suggests that (Cu, N) codoped TiO2/g-C3N4 heterostructure is a preferable visible-light photocatalyst.