Co-doped Films Research Articles

Elaboration and Characterization of Ni and Al Co-Doped Sno2 Thin Films Prepared by Spray Pyrolysis Technique for Photovoltaic Applications

Elaboration and Characterization of Ni and Al Co-Doped Sno2 Thin Films Prepared by Spray Pyrolysis Technique for Photovoltaic Applications

Optical and Electrochromic Analysis of (Al-B) Co-Doped and Un-Doped V2o5 Thin Films

Optical and Electrochromic Analysis of (Al-B) Co-Doped and Un-Doped V2o5 Thin Films

Exploring the Microwave Assisted Sol-Gel Synthesized (Al, Co) Co-Doped Iron Oxide Thin Films for Detailed Impedance and Magnetodielectric Rsposnse

Exploring the Microwave Assisted Sol-Gel Synthesized (Al, Co) Co-Doped Iron Oxide Thin Films for Detailed Impedance and Magnetodielectric Rsposnse

Fabrication and the impact of Fe and Al substitution on structural, morphological, vibrational and optical properties of Fe: Al co-doping zinc oxide nanostructured thin films developed by Arduino based spin coating device

Iron (Fe) and Aluminum (Al) co-doping nanostructured Zinc oxide (ZnO) films were fabricated at various Fe doping concentrations (3 wt%, 5 wt%, and 7 wt%) using the Arduino based spin coating device. In this report, the influence of Fe doping concentration on crystal microstructure and optical properties of Fe: Al co-doping ZnO films were investigated. The structural and optical characteristics of the material were determined using x-ray XRD and UV–VIS spectroscopy. SEM-EDS analysis was used to determine the surface morphology and elemental composition. XRD analysis confirmed the existence of a polycrystalline hexagonal ZnO phase. When the Fe content was increased, it was found that the crystalline quality of the deposited films deteriorated. The optical spectra revealed a transparency range of 85% to 75%. The film with Fe 7 wt% and Al wt3% dopant concentrations exhibited an optical band gap of 3.30 eV. Non-linear optical properties such as non-linear refractive index, non-linear susceptibility using the linear refractive index and energy gap were calculated. The linear refractive index was determined using a variety of models. The non-linear optical properties observed demonstrated a significant dependency on dopant concentrations. The non-linear refractive index and non-linear susceptibilities of the deposited co-doping films are 4.12×10-11-4.67×10-11esu and 2.54×10-12-2.92×10-12esu respectively. SEM analysis of all films demonstrates the growth of nanoscale crystal grains. FTIR spectroscopy verified the zinc oxide metallic bond formation in (Fe, Al) co-doping ZnO thin films.

Fabrication and luminescence properties in Yb –Tb co-doped a-SiCO thin films

Fabrication and luminescence properties in Yb –Tb co-doped a-SiCO thin films

Nitrogen and Bromide Co-Doped Hydroxyapatite Thin Films with Antimicrobial Properties

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp), due to its high biocompatibility, is widely used as biomaterial. Doping with various ions of hydroxyapatite is performed to acquire properties as close as possible to the biological apatite present in bones and teeth. In this research the results of a study performed on thin films of hydroxyapatite co-doped with nitrogen and bromine (NBrHAp) are presented for the first time. The NBrHAp suspension was obtained by performing the adapted co-precipitation method using cetyltrimethylammonium bromide (CTAB). The thin layers of NBrHAp were obtained by spin-coating. The stability of the NBrHAp suspension was examined by ultrasound measurements. The thin layers obtained by the spin-coating method were examined by scanning electron microscopy (SEM), optical microscopy (OM), and metallographic microscopy (MM). The presence of nitrogen and bromine were highlighted by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) studies. Fourier transform infrared spectroscopy (FTIR) was used to highlight the chemical status of nitrogen and bromine. In addition, the powder obtained from the NBrHAp suspension was analyzed by XRD. Moreover, the in vitro antimicrobial activity of the NBrHAp suspensions and coatings was investigated using the reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231. The results highlighted the successful obtainment of N and Br co-doped hydroxyapatite suspension for the first time by an adapted co-precipitation method. The obtained suspension was used to produce pure NBrHAp composite thin films with superior morphological properties. The NBrHAp suspensions and coatings exhibited in vitro antimicrobial activity against bacterial and fungal strains and revealed their good antimicrobial activity.

Influence of the charge compensation effect on the metal–insulator transition of Mg-W co-doped VO2

Cation co-doping was proved an effective approach to reduce the metal–insulator transition (MIT) temperature (θc) of vanadium dioxide (VO2) for realizing excellent optical switching properties near room temperature, but its mechanism is remaining a great challenge. Herein, the Mg-W co-doped VO2 films are fabricated through hydrothermal growth. By changing the Mg content with maintaining 1 at% W doping level, it is observed that Mg dopants raise the θc of co-doped VO2 at a rate of ∼ 22 ℃ per at% Mg as the Mg content is less than ∼ 1 at%, but loses efficacy more than 1 at% Mg. The resistance of the co-doped VO2 films show the similar variation trend. The valence-band XPS spectra indicate that the Mg dopants counteract the VBE uplifting of VO2 caused by W dopants, consequently enlarging the optical band gap of W-doped VO2, which would partially explain the improvement of the visible light transmittance of W-doped VO2 induced by Mg dopants. The results clearly evidence that the charge compensation takes effect in the co-doped VO2, demonstrating the co-doping of high- and low-valent cations is unfavorable for effectively decreasing θc of VO2, and reveal the electron doping plays a key role in reducing θc.

Chiral Thermally Activated Delayed Fluorescence Emitters-Based Efficient Circularly Polarized Organic Light-Emitting Diodes Featuring Low Efficiency Roll-Off.

Direct emission of circularly polarized light from organic light-emitting diodes (OLEDs) is a research hotspot as it could increase the efficiency and significantly simplify device architecture of OLED-based 3D displays. In this study, R/S-OBS-Cz and R/S-OBS-TCz with axial chirality were efficiently prepared by using a stable chiral octahydro-binaphthol unit, carbazole/3,6-ditert-butylcarbazole donors, and a 5,5,10,10-tetraoxide acceptor. The chiral unit-acceptor-donor structure provides them not only thermally activated delayed fluorescence (TADF) characteristics with minor singlet-triplet energy gaps of 0.04 and 0.05 eV but also obvious circularly polarized photoluminescence (CPPL) phenomenon with dissymmetry factors of 8.7 × 10-4 and 6.4 × 10-4 in codoped films. Meanwhile, the CP-OLEDs prepared by enantiomers exhibit good device performances with the maximum external quantum efficiency reaching 20.3% and ideal efficiency roll-off as well as obvious CPEL properties with a |gEL| factor up to 1.0 × 10-3.

White, blue, violet, and other colors from Tm3+/Tb3+/Eu3+ co-doped polymorph SrAl2O4 films, deposited by ultrasonic spray pyrolysis technique

SrAl2O4: Tm3+, SrAl2O4: (Tb3+; Eu3+) and SrAl2O4: (Tb3+; Eu3+; Tm3+) films were deposited by ultrasonic spray pyrolysis (USP) method at 550 °C and subsequently heat-treated at 800 °C. XRD characterization showed a monoclinic/hexagonal polymorph phase of these films with orthorhombic Sr4Al14O25 as secondary phase. The incorporation of Tm3+ ions in strontium aluminate host lattice generated emissions of blue color for photoluminescence and violet color for cathodoluminescence. The violet emission was associated to the electronic transition from 1I6 energy level of Tm3+. Photoluminescence of the SrAl2O4: (Tb3+; Eu3+) films resulted in two different colors, white emission was observed when excited with 210 nm and bluish-white emission was achieved by exciting with 275, and 286 nm. When three dopant ions (Tm3+; Tb3+; Eu3+) were incorporated inside strontium aluminate host lattice, it was observed (exciting under 252 nm) white photoluminescence emission (x = 0.3377, y = 0.3294); for excitation wavelengths (λexc) = 262, 315 and 375 nm, emissions in different shades of blue-green were achieved. Quantum efficiencies between 48 and 57% were obtained.

Melioration of Electrical and Optical Properties of Al and B Co-Doped ZnO Transparent Semiconductor Thin Films

Undoped, Al-doped and Al-B co-doped ZnO transparent semiconductor thin films were deposited on glass substrates by sol-gel method and spin coating technique. This study investigated the influence of Al (2 at.%) doping and Al (2 at.%)-B (1 or 2 at.%) co-doping on the microstructural, surface morphological, electrical and optical properties of the ZnO-based thin films. XRD analysis indicated that all as-prepared ZnO-based thin films were polycrystalline with a single-phase hexagonal wurtzite structure. The substitution of extrinsic dopants (Al or Al-B) into ZnO thin films can significantly degrade the crystallinity, refine the microstructures, improve surface flatness, enhance the optical transparency in the visible spectrum and lead to a shift in the absorption edge toward the short-wavelength direction. Experimental results showed that the Al-doped and Al-B co-doped ZnO thin films exhibited high average transmittance (>91.3%) and low average reflectance (<10%) in the visible region compared with the ZnO thin film. The optical parameters, including the optical bandgap, Urbach energy, extinction coefficient and refractive index, changed with the extrinsic doping level. Measured results of electrical properties revealed that the singly doped and co-doped samples exhibited higher electron concentrations and lower resistivities than those of the undoped sample and suggested that 2 at.% Al and 1 at.% B were the optimum dopant concentrations for achieving the best electrical properties in this study.

Single-shot imaging of ultrafast all-optical magnetization dynamics with a spatiotemporal resolution.

We present a laboratory system for single-shot magneto-optical (MO) imaging of ultrafast magnetization dynamics with less than 8fs temporal, micrometer spatial resolutions and a MO Faraday's rotation sensitivity of 4 mdeg/μm. We create a stack of MO images repeatedly employing a single pair of pump and defocused probe pulses to induce and visualize MO changes in the sample. Both laser beams are independently wavelength-tunable, allowing for a flexible, resonant adjustable two-color pump and probe scheme. To increase the MO contrast, the probe beam is spatially filtered through a 50 μm aperture. We performed the all-optical switching experiment in Co-doped yttrium iron garnet films (YIG:Co) to demonstrate the capability of the presented method. We determine the spatiotemporal distribution of the effective field of photo-induced anisotropy, driving the all-optical switching of the magnetization in the YIG:Co film without an external magnetic field. Moreover, using this imaging method, we tracked the process of the laser-induced magnetization precession.

Impact of Na and/or Sb on the CTS thin films and solar cell performance

Cu2SnS3 (CTS) thin films were synthesized onto a soda lime glass substrate coated molybdenum by sulfurization the Cu–Sn stacks were prepared using RF sputtering. The influence of Na-doped CTS, Sb-doped CTS, and Sb+Na co-doped CTS films on their physical properties has been investigated. The undoped and doped films have been illustrated in a monoclinic structure with no shifts in peak position. Larger grain size has been obtained with Sb doping compared to undoped CTS. Enhancement in photoluminescence sharpening and yield spectra were indicated in the existence of Na and/or Sb. The power conversion efficiency was enhanced by the addition of Na and/or Sb to the CTS absorber layer, from 0.32% for undoped CTS to 1.54, 1.89 and 0.76% for Na, Sb, and co-doping CTS, respectively. As a result, the influence of doping has improved all cell efficiency with an increasing ratio of 381, 490, 137% with Na, Sb, and co-doping, respectively.

SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE Co-DOPED ZnO THIN FILMS PREPARED BY CHEMICAL SPRAY PYROLYSIS FOR OPTOELECTRONIC APPLICATIONS

ZnO:Co thin films were synthesized by the chemical spray pyrolysis (CSP) on glass substrates. Then, investigated the impact of Co doping concentration on its physical properties. XRD analyses show that all films have a polycrystalline structure of hexagonal ZnO. The crystallite size increased from 18[Formula: see text]nm to 25[Formula: see text]nm with Co doping concentrations. Furthermore, the unit cell volume increased from 47.485[Formula: see text]Å to 47.831[Formula: see text]Å, and the Zn–O bond length expanded from 1.97588[Formula: see text]Å to 1.98071[Formula: see text]Å. SEM observations reveal the formation of fiber-like nanostructures in the Co-doped thin films. The diameter of nanofibers increased with Co doping concentration from 260[Formula: see text]nm to 700[Formula: see text]nm. The optical characteristics were studied by the UV-Visible spectrophotometer and manifest the optical transparency vary with Co doping. In addition, the band gap decreases from 3.27[Formula: see text]eV to 2.73[Formula: see text]eV with increasing Co doping concentrations. The conductivity varied from 3.35[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] to 19.88[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] with Co doping concentrations. Empirical models were proposed to evaluate the correlated variables with excellent accuracy with the experimental data. The best result was accomplished in ZnO:Co1% films, where good transparency and high conductivity were achieved.

Synergistic Effect of Codoped Nickel Oxide Hole–Transporting Layers for Highly Efficient Inverted Perovskite Solar Cells

Perovskite Solar Cells In article number 2100243 Do–Hyung Kim, Hyo Jung Kim, and co-workers systematically investigate Li:Cu doped NiOx films and their characteristics as hole transporting layers for inverted perovskite solar cells (PSCs). The co-doped NiOx films exhibit enhanced optical/electrical properties and show favorable interfacial properties forming high-quality perovskite films which results in high-efficiency inverted PSCs.

Preparation and Characterization of (Al, Fe) Codoped ZnO Films Prepared by Sol–Gel

In this research, Al-doped and (Al, Fe) codoped ZnO films were prepared on glass substrate by the sol–gel method. The surface morphology, structure, and optical property were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Ultraviolet-Visible-Near-infrared (UV-Vis-NIR) spectroscopy. The film surface morphologies all exhibited granular characteristics. With the Fe doping concentration increasing, the codoped films had smaller grain size and tended to be smoother. XRD analysis revealed that all films had a hexagonal wurtzite structure. The codoping can contribute to more Al and Fe ions entering the ZnO crystal structure, but result in the crystalline degree of the films decreasing. XPS results showed that the Al and Fe irons in the films exist in the form of trivalent. Moreover, the doped films had higher transmission, especially for codoped (Fe:Al = 3) film, but their absorption edge shifted to the short-wavelength direction.

Magnetoresistance and its relaxation of nanostructured La-Sr-Mn-Co-O films: Application for low temperature magnetic sensors

The results of magnetoresistance (MR) and resistance relaxation of nanostructured La1-xSrx(Mn1-yCoy)zO3 (LCMCO) films doped with different Co amount (Co/(La + Sr) = 0.06; 0.12; 0.14) while keeping constant Sr (x = 0.2) deposited by Pulsed Injection MOCVD technique, are presented and compared with the reference manganite La0.8Sr0.2MnzO3 (LSMO) film. The MR was investigated in pulsed magnetic fields up to 25 T in the temperature range 4–200 K while the relaxation processes were studied in pulsed fields up to 10 T and temperatures in the range of 100–300 K. It was demonstrated that at low temperatures the MR(%) and sensitivity S(mV/T) of Co-doped films have significantly higher values in comparison with the LSMO ones, and increases with increase of Co/(La + Sr) ratio. The observed temperature-insensitive MR in the range of 4–200 K suggests possibility to use these films for sensors applications. The magnetic memory effects were investigated as resistance relaxation processes after the switch-off of the magnetic field pulse. The observed ‘fast’ (~300 μs) resistance relaxation was analyzed by using the Kolmogorov–Avrami–Fatuzzo model, taking into account the reorientation of magnetic domains into their equilibrium state, while the ‘slow’ process (>ms) was explained by using the Kohlrausch–Williams–Watts model considering the interaction of the magnetic moments in disordered grain boundaries. It was concluded that Co-doped nanostructured manganite LSMCO films having a higher sensitivity and lower memory effects in comparison with the LSMO films could be used for the development of pulsed magnetic field sensors operating at low temperatures.

Thickness dependence of structural and superconducting properties of Co-doped BaFe2As2 coated conductors

SummaryHigh-quality Co-doped BaFe2As2 thin films with thickness up to 2 μm were realized on flexible metal tapes with LaMnO3 as buffer layers fabricated by an ion beam-assisted deposition technique. Structural analysis indicates that increasing thickness does not compromise the film crystallinity, except for a small amount of impurities. Two types of thickness dependence of critical current density (Jc) were found: one is almost thickness independent in the range of 0.6–1.5 μm and the other is highly thickness dependent. In addition, the maximum value for crucial current Ic at 9 T and 4.2 K is about 55 A/12 mm-W for the 1.5-μm-thick film. Anisotropic Ginzburg–Landau scaling demonstrates that dominant pinning centers develop from correlated to uncorrelated with increasing film thickness. The further theoretical analysis shows that with film thickness increasing the pinning mechanism evolves progressively from a δl pinning to the δTc pinning mechanism.

Structural, morphological, optical, and electrochemical properties of Co-doped CeO2 thin films

Undoped and Co-doped cerium dioxide (CeO2)thin films with different doping rates (x = 2, 4, 6%) were successfully elaborated using the spray pyrolysis (SP) technique on the glass substrate at the optimized temperature (450 ± 5) °C. Cobalt effect on microstructural, morphological, optical, and electrochemical behavior of CeO2 material was studied using X-ray diffractometer (XRD), micro-Raman spectroscopy, scanning electron microscope (SEM), energy dispersive analysis by X-ray (EDS), UV–Vis–NIR spectrophotometer, and Volta Lab system (VM4). XRD pattern shows the cubic structure fluorite type of the prepared samples, with (111) as preferred orientation. Raman spectra confirm XRD findings by the peak located at 462 cm−1 which corresponds to the active mode F2g of the cubic fluorite structure and reveal a small band after F2g mode coming from the vacancy oxygen. SEM images show densely uniform grains with some cracks and aggregates. EDS data confirm the presence of Ce, O, and Co elements in elaborated samples. The optical results show good transparency in the visual domain (≃70%) and a band gap starting from 3.18 eV for the undoped sample and decreases with increasing Co rate to attain 2.82 eV for 6%. Cyclic voltammetry results reveal that doping with Co increases the ion storage capacities of samples. The computational data obtained using WIEN2k software support our experimental results.

All-optical magnetic recording in garnets using a single laser pulse at L-band telecom wavelengths

Ultrafast photo-magnetism in dielectric garnets reveals a possibility to perform magnetization switching with a single laser pulse. We demonstrate ultrafast photo-magnetic switching in Co-doped iron garnet films at wavelengths relevant to the more-enabled optical L-band window. We studied both photo-induced magnetization precession and switching of magnetization within the near-infrared spectral range using magneto-optical tools. Single laser pulse switching of magnetization around the 1590 nm wavelength has been found in a narrow resonance band using magneto-optical imaging. The high efficiency of this switching, along with a very low-photon absorption in the L-band, makes this phenomenon interesting for both all-optical magnetic recording and data transfer using telecom systems.

Preparation and characterization of TiO2 thin film electrode for optoelectronic and energy storage Potentials: Effects of Co incorporation

In this study, thin film samples of undoped and Co-doped titanium oxide (TiO2) nanostructures were deposited on conducting ITO glass substrate. Influence of Co-dopant on TiO2 thin film for potential application in optoelectronic and supercapacitor devices was investigated. Microstructural studies revealed Co-doped TiO2 films possess fewer and narrower pores. Particles of the Co-doped TiO2 films are relatively larger, closely packed without any observable pin hole or crack. Increased dopant concentrations also improved the crystallinity and average grain sizes of the films but with slight distortions in their crystal lattices. Films’ crystal sizes lied between 47.51 and 57.23 nm. Elemental composition study confirmed the presence of all elements attributable to the films accordingly. Optical studies demonstrated the films’ high transparency across the visible light spectrum and that it is dependent on dopant concentration. Red shift towards higher wavelengths is observed in the absorption band edges upon dopant increasing concentration. The result also led to tunning of bandgaps and Urbach energies of TiO2 structure from 3.28 to 3.22 eV and 2.37 to 1.95 eV, respectively. The electrochemical properties of the deposited Co-doped and pure TiO2 thin films were investigated with the aid of analyses of cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopic (EIS) studies. The study showed that the film electrodes demonstrated appreciable high-rate energy storage capability and stability. It also revealed enhanced areal capacitance and capacity of 15.86 mF cm−2 and 9.19 mAh cm−2, respectively. The study demonstrated successful coating of the Co-doped TiO2 nanostructures on ITO glass substrate and unveiled the influence of cobalt dopant on some properties of TiO2 thin film suitable for application in optoelectronics and supercapacitor.