Thin ZnO Layer Research Articles

Evaluating the impact of microstructure modifications on thin film photoelectric properties

Microstructure modifications on thin photoelectrical properties refers to changes in the microscopic structure of thin films that affect their ability to convert light into electricity. This study investigates the deposition and post-treatment effects in the electric and visual qualities of GZO, IZO, and ZnO thin layers, aiming to enhance their applicability in electronic and optoelectronic devices, according to the X-raydiffraction (XRD) examination. Thin films were deposited on glass substrates using magnetic sparking at thicknesses of 300 nm and 500 nm, followed by treatments like wet aging and annealing at 220 °C. The results showed significant improvements in crystallinity and optical characteristics, with ZnO films exhibiting a preferred (003) orientation. IZO films demonstrated notable mobility at 10.96 cm2/V-sec and resistivity of 2.49×10⁻3 ohm-cm. The novelty of this research is the novel integration of wet aging and low-temperature annealing, that notably improves thin film efficiency while maintaining structural integrity. The findings indicate that post-treatment significantly enhances the properties of these thin films, suggesting their potential for various electronic applications.

Stability Properties of Inverted Organic Solar Cells Prepared with a ZnO Buffer Layer

Organic solar cells (OSCs) of inverted structure (IOSC) were designed to enhancement the solar cell efficiency and stability in organic based solar cell. IOSC was built with the structure of Au/P3HT:PCBM/ZnO/ITO. ZnO thin layers were fabricated on ITO electrodes using the unbalanced magnetron sputtering method. ZnO layer is used as the buffer layer in this structure to prevent oxidation by UV light to the interface of the organic layer and reduce the energy barrier, allowing electron to be easily transferred between the ITO energy level and the organic acceptor energy level (LUMO). ZnO films are also used as a barrier layer to prevent hole injection from P3HT due to the lack of charge carrier recombination. XRD results exhibited that the particle size in ZnO layers increased as the substrate temperature increased. The conversion efficiency of IOSC improved with increasing ZnO substrate temperature. Moreover, compared to the existing device, the IOSC using a ZnO buffer layer was in a stable state for a longer period of time. After about 7 days, it woas found that the Voc of the hybrid solar cells remained almost constant over time and under all conditions. As a result, the ZnO film in the OSC plays an important role for protecting the organic layer of OSCs and enhancing the efficiency.

Stability investigation of Eu3+ doped CaF2 thin film with ZnO coating under electron beam irradiation

Eu3+ ion doped CaF2 thin film was successfully prepared using the hydrothermal method and coated by a spin coating technique. A thin layer of ZnO was deposited on the Eu3+ doped CaF2 thin film by pulsed laser technique. Incorporation of the dopant into the CaF2 crystal was confirmed by x-ray powder diffraction and x-ray photoelectron spectroscopy (XPS). Excitation of the film at 227 nm produced the characteristic emissions of Eu3+ ions. The stability of the film under electron beam bombard was studied using Auger electron spectroscopy, cathodoluminescence (CL), and XPS. The CL and Auger peak-to-peak heights (APPHs) data were collected concurrently using the same electron beam. The APPH of Ca and O increased, while that of F decreased, which indicated the conversion of CaF2 to CaO. The CL emission decreased initially during degradation and stabilized beyond 48 C/cm2 for the film with the ZnO coating. XPS analysis also indicated the dissociation of the fluoride compounds and subsequent formation of oxide compounds such as CaO and EuO after electron beam degradation.

Optical and Electrochemical Properties of a Nanostructured ZnO Thin Layer Deposited on a Nanoporous Alumina Structure via Atomic Layer Deposition.

This study explores the optical and electrochemical properties of a ZnO coating layer deposited on a nanoporous alumina structure (NPAS) for potential multifunctional applications. The NPAS, synthesized through an electrochemical anodization process, displays well-defined nanochannels with a high aspect ratio (~3000). The ZnO coating, achieved via atomic layer deposition, enables the tuning of the pore diameter and porosity of the NPAS, thereby influencing both the optical and electrochemical interfacial properties. A comprehensive characterization using photoluminescence, spectroscopy ellipsometry and impedance spectroscopy (with the sample in contact with NaCl solutions) provides insights into optical and electrochemical parameters, including the refractive index, absorption coefficient, and electrolyte-ZnO/NPAS interface processes. This research demonstrates potential for tailoring the optical and interfacial properties of nanoporous structures by selecting appropriate coating materials, thus opening avenues for their utilization in various technological applications.

Efficient Quantum Dot Infrared Photovoltaic with Enhanced Charge Extraction via Applying Gradient Electron Transport Layers

AbstractPbS quantum dot (QD) infrared (IR) solar cells that can absorb low‐energy photons are promising photovoltaic devices to improve utilization of sunlight energy by broadening absorption range of the sunlight spectrum to short‐wave infrared region. For PbS QD photovoltaics, depleted heterojunction established between photoactive layer and ZnO electron transport layer (ETL) is critical to determine the performance of devices. However, undesired defects in ZnO films and mismatched energy levels have limited the improvement of device properties. Herein, a novel and simple gradient ZnO ETL is developed for achieving high‐performance QD IR solar cells by depositing a Cs‐doped ZnO thin layer on the pristine ZnO film. The resulting gradient ETL exhibits significantly suppressive trap states and a much smoother surface, efficiently reducing the trap‐assisted nonradiative recombination at the interfaces. Meanwhile, realigned energy levels of the gradient ZnO ETL facilitate the transport and extraction of photogenerated carriers. As a result, the champion device shows a high IR open circuit voltage (VOC) of 0.446 V and IR power conversion efficiency (PCE) of 1.27% under 1100 nm filtered illumination. The VOC and PCE are 0.507 V and 11.04% under AM1.5 illumination, respectively. These results demonstrate a promising strategy for exploiting high‐performance infrared optoelectronic devices.

Structural, morphological and photoluminescent properties of annealed ZnO thin layers obtained by the rapid sol-gel spin-coating method

Structural, morphological and photoluminescent properties of annealed ZnO thin layers obtained by the rapid sol-gel spin-coating method

Application of the photoluminescent ZnO thin layers in optical immunosensors. Original optical effects

Application of the photoluminescent ZnO thin layers in optical immunosensors. Original optical effects

Tuning the optical properties of Ln3+-doped-Y2O3@ZnO@Au core-shell heterostructures for visible-to-NIR photon harvesting

Here, compact Yb3+-Er3+-Tm3+ doped Y2O3 phosphor microspheres were synthesized by solvothermal method which gave emission in the entire visible region under 980 nm excitation. The effect of doping alkali ions like lithium on the upconversion emission of YYET phosphors is investigated. An epitaxial layer of ZnO is grown around the YYETL (Li+ doped YYET) microspheres by hydrothermal technique. An analysis of the influence of the ZnO shell thickness on the upconversion emission of core microspheres is done. Initial growth of a thin layer of ZnO on the YYETL microspheres causes enhancement in upconversion emission due to passivation of surface defects of core microspheres. Quenching of anti-Stokes emission occurs for thicker ZnO shell coating. Further, it is decorated with AuNPs to study the effect of plasmonics on the optical property of the developed heterostructure. The overlap between the upconversion emission spectra of core microspheres and the LSPR peak of AuNPs modulates the property of the entire structure. The optimized samples were checked for photocatalytic application by degradation of Rh6G dye under solar irradiation. YYETL@ZnO@Au core-shell samples exhibited highest rate constant of 0.00395 min−1, which is attributed to better exploitation of the UV–Vis-NIR region of the solar spectrum by all three components of the heterostructure.

Enhancement of the efficiency of solar collector by SiO2, TiO2, and ZnO thin films layers

Most scientific researchers are motivated to develop alternative energy applications and raise their efficiency as a result of rising global warming and pollution from traditional energy sources. In this study, Nanocoating thin films of ` have been prepared on different substrates (stainless steel 316 L, commercially pure Ti, Si-Wafer(100) and glass). Magnetron sputtering deposition technique at 2.8 × 10–7 Torr vacuum has been used to synthesize the nanocoated thin films. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Atomic Force Microscopy (AFM), and UV–visible radiation tests have been used to characterize the thin films deposited. The investigation results showed that the thin films deposited do not have microcracks or defects with a uniform and homogenous structure at 400 nm magnification. It has a nanoparticle grain size of 60–90 nm with a crystal structure for TiO2, SiO2, and ZnO films. ZnO films have coarser grain and more aggregation than the other films. The highest efficiency of the collector was recorded for a collector integrated with ZnO thin-film. The efficiency of the ZnO-coated collector was about 66 % at midday compared to the conventional system (no thin film), which was 39 %.

The Optical Properties of Thin Film Alloys of ZnO, TiO2 and ZrO2 with Al2O3 Synthesised Using Atomic Layer Deposition

In this work, the results of ellipsometric studies of thin films of broadband oxides (ZnO, TiO2, ZrO2) and broadband oxides doped with Al2O3 (Al2O3–ZnO, Al2O3–TiO2, Al2O3–ZrO2) are presented. All layers have been produced using the atomic layer deposition method. Ellipsometric studies were performed in the wavelength range of 193–1690 nm. Sellmeier and Cauchy models were used to describe the optical properties of the tested layers. Dispersion dependencies of refractive indices were determined for thin layers of broadband oxides on silicon substrates, and then for layers of Al2O3 admixture. The EDX investigations enabled estimation of the composition of the alloys. The Bruggeman effective medium approximation (EMA) model was used to determine the theoretical dependencies of the dispersion refractive indices of the studied alloys. The refractive index values determined using the Bruggeman EMA model are in good agreement with the values determined from the ellipsometric measurements. The doping of thin layers of ZnO, ZrO2 and TiO2 with Al2O3 enables the creation of anti-reflective layers and filters with a specific refractive index.

Pump-probe reflectivity studies of ultrashort laser-induced acousto-mechanical strains in ZnO films

In the current work we report on the generation of acoustic strains in thin ZnO layers using optoacoustic transduction of ultrashort laser pulses into acoustic waves on an Au thin film transducer. After absorption of energy by the electron system of the metal, energy conversion, thermal expansion and mechanical deformation takes place. The generation and propagation of the induced acoustic strains are monitored in time via a degenerate pump-probe transient reflectivity optical setup at 800 nm, as opposed to most commonly used schemes that employ different wavelengths for the pump and probe beams, mostly in the vicinity of ZnO maximum absorption. The experimental results include energy relaxation times and phonon scattering frequencies and are supported by a thermal vibro-acoustic finite element model. The model is based on the combination of a revised two-temperature approach and elasticity theory, and considers anisotropic properties for the ZnO film and the computation of the elastic wave velocity for the first time. The outcomes are discussed in the context of electron–phonon coupling factors and other material properties. A good agreement between the experimental findings and the results from the numerical simulations has been established, regarding outcomes like the mean velocity of the strain waves, establishing a novel characterization method applicable to a variety of materials and structures.

INVESTIGATION ON THE CRYSTALLINITY AND OPTOELECTRONIC PROPERTIES OF THIN FILMS OF ZNO/MAPBX3HETEROJUNCTIONSYNTHESIZED VIA THE SPIN-COATING METHOD

In this paper, thin layers of ZnO were deposited onto fluorine-doped tin oxide (FTO) substrates. Subsequently, different layers of perovskite (MAPbX3, X = I, Br, Cl) were spin-coated onto these ZnO layers. The resulting layers were characterized using X-ray diffraction (XRD), UV-Visible spectroscopy, and scanning electron microscopy (SEM). Special attention was given to the surface topography, the crystallinityand optoelectronic properties.XRD analysis of all the thin layers showed two diffraction peaks for the ZnO/MAPbX3 heterojunction corresponding to the crystallographic planes (100) and (200). The ZnO/MAPbBr3 peaks were more intense than the peaks from the ZnO/MAPbI3 and ZnO/MAPbCl3 samples. SEM images showed the crystalline nature of the produced thin layers. The grain size of the ZnO/MAPbBr3 sample was approximately 747.00 nm, while those of the ZnO/MAPbI3 and ZnO/MAPbCl3 samples were 412.00 nm and 330.55 nm, respectively. UV-visible characterization demonstrated that the iodine-based sample had the highest solar radiation absorption and had the smallest bandgap, with Eg = 1.95 eV.

Facile and versatile fabrication process for AgNW/GZO transparent composite electrodes for photovoltaic applications by atmospheric pressure plasma jet

Transparent conductive oxide (TCO) must have high electrical conductivity and optical transmittance. Using higher doping concentrations improves the conductivity but often at the expense of transmittance in the near-infrared regime. Using thicker film to improve the conductivity is not preferable as it significantly reduces the transmittance. Silver nanowire (AgNW)/ TCO composite film has been proposed as a viable method to address this dilemma. However, AgNWs often require additional thermal treatment to weld the nanowires to reduce the contact resistance. Also, thermal treatment apparatus, such as lasers, cannot be easily integrated into the TCO deposition setup, adding extra cost for handling samples. Here we use an atmospheric pressure plasma jet (APPJ) to fabricate AgNW/ TCO composite films—APPJ successfully welds the AgNWs and covers them with a thin gallium-doped ZnO or GZO protective layer simultaneously. The AgNW weight significantly affects the optoelectronic and morphological properties and can be tailored to fit the requirements of particular photovoltaic applications. Our perovskite solar cells with the AgNW/GZO front electrodes exhibit a ∼21% increase in power conversion efficiency. Furthermore, unlike conventional methods, our approach is vacuum-free and does not require additional processes, such as lasers, to treat the AgNW network, which may greatly reduce operational complexity.

Structure and Optical Properties of Transparent Cobalt-Doped ZnO Thin Layers

Transparent thin layers of cobalt-doped ZnO were produced with the pulsed laser deposition method. The cobalt content of the original solid solution was 20% at. The crystallographic structure was examined by X-ray diffraction, which showed that the fabricated layers crystallized in the wurtzite phase and had a dominant orientation along the a-axis. The texture coefficient (increasing from F = 0.08 for the non-annealed layer to F = 0.94 for the annealed layer at 400 °C) and grain size (D = 110 ÷ 140 nm) were calculated. Optical constants, such as the refractive index n (1.62) and the extinction coefficient k (0.1 ÷ 0.4), were determined from the ultraviolet–visible–near-infrared transmission spectrum using the envelope method. The value of the optical band gap was determined, which is lower than for pure ZnO. Increasing the annealing temperature of the ZnO:Co layer increases the Urbach energy from 0.20 to 0.25 eV, which shows the difference in the type of growth defects in the ZnO matrix.

Atomic layer deposition of ZnO on Li1.3Al0.3Ti1.7(PO4)3 enables its application in all solid-state lithium batteries

BackgroundAll-solid-state Li batteries (ASSLBs) are emerging as potential electrochemical energy storage devices for next-generation large-scale electrical power systems. In particular, Li1.3Al0.3Ti1.7(PO4)3 (LATP) is an efficient cost-effective solid-state electrolyte with high ionic conductivity for high energy density and safety ASSLBs. Since LATP is unstable verus metallic Li. Therefore, the application of Li-based all-solid-state batteries is practically limited. MethodsAs a possible solution to overcome the LATP instability, the interface was modified by adding a 5 nm thin ZnO layer on LATP using the atomic layer deposition (ALD) technique. Significant FindingsThe ZnO layer reduces the observed overpotential in a Li|ZnO@LATP|Li symmetric cell compared to an unmodified LATP-based cell. In contrast to the unmodified LATP-based Li cells, the ZnO-modified symmetric LATP-based Li cells show stable cycling for more than 500 h without a short circuit. The full-cell configuration of the LiFePO4|ZnO@LATP|Li system showed a reversible capacity of 156 mAh/g over 50 cycles and exposed good capacity retention (98.79% after 50 cycles) during the cycling test. The results indicate that ZnO coating by ALD on LATP could overcome the stability issues of pristine LATP versus metallic Li. Therefore, this work will lead to prove the simple manner of interfacial modification and improvement of electrochemical performance of inorganic oxide based solid electrolytes for all-solid-state lithium battery applications.

Self-Organization Effects of Thin ZnO Layers on the Surface of Porous Silicon by Formation of Energetically Stable Nanostructures.

The formation of complex surface morphology of a multilayer structure, the processes of which are based on quantum phenomena, is a promising domain of the research. A hierarchy of pore of various sizes was determined in the initial sample of porous silicon by the atomic force microscopy. After film deposition by spray pyrolysis, ZnO nanoclusters regularly distributed over the sample surface were formed. Using the electron paramagnetic resonance (EPR) method it was determined that the localization of paramagnetic centers occurs more efficiently as a result of the ZnO deposition. An increase in the number of deposited layers, leads to a decrease in the paramagnetic center relaxation time, which is probably connected with the formation of ZnO nanocrystals with energetically stable properties. The nucleation and formation of nanocrystals is associated with the interaction of particles with an uncompensated charge. There is no single approach to determine the mechanism of this process. By the EPR method supplemented with the signal cyclic saturation, spectral manifestations from individual centers were effectively separated. Based on electron paramagnetic resonance and photoluminescence studies it was revealed that the main transitions between energy levels are due to oxygen vacancies and excitons.

Electric characterization of transition metal (Co, Ni, Fe) doped ZnO thin layers prepared by atomic layer deposition

Doping of ZnO with different ions enables efficient control of its optical, electrical and magnetic properties. ZnO thin films doped with 3d transition metals have potential to be used as diluted magnetic semiconductors. In this work, dielectric and electrical properties of transition metal (Ni-, Co- or Fe-) doped ZnO thin films prepared by atomic layer deposition (ALD) have been studied. Standard capacitance-voltage (C-V) and current-voltage (I-V) as well as capacitance-frequency (C-f) characteristics have been measured. Some important parameters, e.g. the concentration of majority carriers N D, barrier height Ф b as well as the built-in potential Vbi are determined. Different polarization effects are considered to explain the strong frequency dependence of dielectric constant.

Surprising Eutectics: Enhanced Properties of ZnO-ZnWO4 from Visible to MIR.

Zinc oxide-zinc tungstate (ZnO-ZnWO4 ) is a self-organized eutectic composite consisting of parallel ZnO thin layers (lamellae) embedded in a dielectric ZnWO4 matrix. The electromagnetic behavior of composite materials is affected not only by the properties of single constituent materials but also by their reciprocal geometrical micro-/nano-structurization, as in the case of ZnO-ZnWO4 . The light interacting with microscopic structural features in the composite material provides new optical properties, which overcome the possibilities offered by the constituent materials. Here remarkable active and passive polarization control of this composite over various wavelength ranges are shown; these properties are based on the crystal orientation of ZnO with respect to the biaxiality of the ZnWO4 matrix. In the visible range, polarization-dependent polarized luminescence occurs for blue light emitted by ZnO. Moreover, it is reported on the enhancement of the second harmonic generation of the composite with respect to its constituents, due to the phase matching condition. Finally, in the medium infrared spectral region, the composite behaves as a metamaterial with strong polarization dependence.

Piezoelectric characteristics of PVA/DL-alanine polycrystals in d33 mode

In this study, polyvinyl alcohol (PVA)-mixed DL-alanine (PVA/DL-alanine) polycrystals are fabricated, and their piezoelectric characteristics in the d33 mode are investigated. The d33 piezoelectric coefficients of the PVA/DL-alanine polycrystals are found to increase with an increase in the weight ratio of DL-alanine, and the PVA/DL-alanine polycrystal composed of PVA and DL-alanine in a weight ratio of 1:3 exhibits a d33 of ∼5pC/N. The piezoelectric characteristics of the PVA/DL-alanine polycrystals are discussed in terms of the crystal structure by employing scanning electron microscopy and X-ray diffraction analyses. To confirm the piezoelectric performance of the polycrystals, the piezoelectric voltages of a piezoelectric device composed of a single layer of ZnO thin film and heterostructured devices consisting of a layer of PVA/DL-alanine polycrystal and a ZnO thin film layer are measured and compared. This study presents PVA/DL-alanine polycrystals as a potential piezoelectric material for bio-friendly piezoelectric-device applications.

Study of CIGS Pseudo-Homojunction Thin Film Solar Cell using SCAPS-1D

The present modelling study reports the performance of defected CIGS pseudo-homojunction thin film solar cell (P-HTFSC) and determines its optimum parameters for high performance using the Scaps-1D software under the AM1.5 illumination and the operating temperature of 300 K. To focus the discussion on the optimal parameters (thickness, doping concentrations, deep/interface defect concentrations and bandgap) for the ZnO, CdS, ODC and CIGS thin film layers, cross sectional (1D) simulations have been performed on the ZnO/CdS/ODC/CIGS P-HTFSC device for obtaining its optimal structure that confers high light-into-electricity conversion efficiency. The four light J-V characteristics (short-circuit current: JSC, open-circuit voltage: VOC, fill factor: FF and conversion efficiency: ) have been used as indicators to evaluate the device performances. Simulation outcomes have proved that for a best performance for CIGS P-HTFSC device, the optimal thickness for CIGS and ODC layers should be small than 2 µm and few nm, respectively, while the optimal defect concentration within the layer should be 1013 cm-3 and between 1013 cm-3-1018 cm-3, respectively.