Aluminum-doped Zinc Oxide Research Articles

Bifacial flexible CIGS thin-film solar cells with nonlinearly graded-bandgap photon-absorbing layers

The building sector accounts for 36% of energy consumption and 39% of energy-related greenhouse-gas emissions. Integrating bifacial photovoltaic solar cells in buildings could significantly reduce energy consumption and related greenhouse gas emissions. Bifacial solar cells should be flexible, bifacially balanced for electricity production, and perform reasonably well under weak-light conditions. Using rigorous optoelectronic simulation software and the differential evolution algorithm, we optimized symmetric/asymmetric bifacial CIGS solar cells with either (i) homogeneous or (ii) graded-bandgap photon-absorbing layers and a flexible central contact layer of aluminum-doped zinc oxide to harvest light outdoors as well as indoors. Indoor light was modeled as a fraction of the standard sunlight. Also, we computed the weak-light responses of the CIGS solar cells using LED illumination of different light intensities. The optimal bifacial CIGS solar cell with graded-bandgap photon-absorbing layers is predicted to perform with 18%–29% efficiency under 0.01–1.0-Sun illumination; furthermore, efficiencies of 26.08% and 28.30% under weak LED light illumination of 0.0964 mW cm−2 and 0.22 mW cm−2 intensities, respectively, are predicted.

Aluminum enhances the oxidative damage of ZnO NMs in the human neuroblastoma SH-SY5Y cell line

Bare and doped zinc oxide nanomaterials (ZnO NMs) are of great interest as multifunctional platforms for biomedical applications. In this study, we systematically investigate the physicochemical properties of Aluminum doped ZnO (AZO) and its bio-interactions with neuroblastoma (SH-SY5Y) and red blood (RBCs) cells. We provide a comprehensive chemical and structural characterization of the NMs. We also evaluated the biocompatibility of AZO NMs using traditional toxicity assays and advanced microscopy techniques. The toxicity of AZO NMs towards SH-SY5Y cells, decreases as a function of Al doping but is higher than the toxicity of ZnO NMs. Our results show that N-acetyl cysteine protects SH-SY5Y cells against reactive oxygen species toxicity induced by AZO NMs. ZnO and AZO NMs do not exert hemolysis in human RBCs at the doses that cause toxicity (IC50) in neuroblastoma cells. The Atomic force microscopy qualitative analysis of the interaction of SH-SY5Y cells with AZO NMs shows evidence that the affinity of the materials with the cells results in morphology changes and diminished interactions between neighboring cells. The holotomographic microscopy analysis demonstrates NMs' internalization in SH-SY5Y cells, changes in their chemical composition, and the role of lipid droplets in the clearance of toxicants.Graphical

Temperature shock to manipulate the optical properties of Al-doped ZnO films

We constructed the 2 × 2 × 2 Aluminum-doped Zinc Oxide (AZO) supercrystal cell structure and developed the temperature shock experiment at −40 °C–85 °C. The results showed that the temperature shock can increase the absorption rate of AZO, decrease the transmittance and the band gap of AZO, and change the density of electronic states near the Fermi level. The AZO films were also subjected to temperature shock of −40°C–85 °C, it shows that the transmittance and band gap of AZO films both decreased after temperature shock. The experimental results show that the temperature shock reduce the transmittance and the band gap width of the AZO films. The results are hoped to be helpful to understand the degeneration and improvement of the optical properties of AZO films under temperature shock loading and predict the performance of AZO films.

A Comprehensive Investigation of the Mechanical and Tribological Properties of AZO Transparent Conducting Oxide Thin Films Deposited by Medium Frequency Magnetron Sputtering.

This paper presents a detailed analysis of aluminium-doped zinc oxide (AZO) thin films and considers them a promising alternative to indium tin oxide in transparent electrodes. The study focusses on critical properties of AZO, including optical, electrical, and mechanical properties, with potential applications in displays, photovoltaic cells, and protective coatings. The deposited AZO thin films are characterised by excellent optical and electrical parameters, with transparency in the visible light range exceeding 80% and resistivity of 10-3 Ω·cm, which gives a high value of figure of merit of 63. Structural analysis confirms the nanocrystalline nature of as-deposited AZO thin films, featuring hexagonal ZnO, orthorhombic Al2O3, and cubic Al2ZnO4 phases. The study includes nanoindentation measurements, which reveal exceptional hardness (11.4 GPa) and reduced elastic modulus (98 GPa), exceeding typical values reported in the literature, highlighting their protective potential. Abrasion tests have shown extraordinary scratch resistance due to the lack of impact on topography and surface roughness up to 10,000 cycles. This comprehensive study demonstrated that as-deposited AZO thin films are multifunctional materials with exceptional optical, electrical, and mechanical properties. The findings open up possibilities for a variety of applications, especially in protective coatings, where the combination of hardness, scratch resistance, and transparency is both rare and valuable.

Photovoltaic performance enhancement of Al/ZnO:Al/i-ZnO/CdS /CIGS/Pt solar cell using SCAPS-1D software

The high-performance Cu(In,Ga)Se2 (CIGS) absorber layer is simulated by the SCAPS-1D software. A CIGS absorber layer, a cadmium sulfide (CdS) buffer layer, intrinsic zinc oxide (i:ZnO), and aluminum-doped zinc oxide (Al:ZnO), also known as transparent conductive oxide (TCO), are all included in the cell structure. These layers are connected to upper/top and back contacts made of aluminum (Al) and platinum (Pt). All optimizations employed in cell structure have a thin layer of Al/ZnO:Al/i-ZnO/CdS/CIGS/Pt. The open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and efficiency (η) were all investigated in this study, along with the effects of back contact, absorber and buffer layer thickness, the absorber layer's acceptor density, the buffer layer's donor density, the absorber and buffer layer's defect densities, performance of interface defect density, series and shunt resistance, and temperature. To achieve optimal performance, it is recommended to set the acceptor and donor densities for the absorber and buffer layers at 1018 cm−3, while maintaining defect densities at 1014 cm−3. These desired densities can be attained by using a window layer thickness of 200 nm, a buffer layer thickness of 40 nm, and an absorber layer thickness of 2500 nm. The optimized model demonstrates photovoltaic (PV) performance characteristics of 0.8975 V for VOC, 34.245732 mA/cm2 for JSC, 86.81% for FF, and 26.68% for power conversion efficiency (PCE) under the AM 1.5 G spectrum. Furthermore, it exhibits a quantum efficiency of 98.86% at visible wavelengths.

Aluminum-doped zinc oxide nanoparticles prepared via nanosecond Nd: YAG laser ablation in water: optoelectronic properties

Aluminum-doped zinc oxide nanoparticles prepared via nanosecond Nd: YAG laser ablation in water: optoelectronic properties

Preparation of Low-Defect Aluminum-Doped Zinc Oxide Nanostructure-Based Compact Layer by Vacuum Ultraviolet Irradiation for Quantum Dot-Sensitized Solar Cells

Preparation of Low-Defect Aluminum-Doped Zinc Oxide Nanostructure-Based Compact Layer by Vacuum Ultraviolet Irradiation for Quantum Dot-Sensitized Solar Cells

The Characteristic of Ph-Sensing of Potentiometric on Zinc Oxide and Aluminium-Doped Zinc Oxide Nanostructures

Numerous investigations have been conducted to increase the sensitivity and stability of metal oxide semiconductors as pH-sensing membranes. This paper will describe the pH sensing and characterisation of zinc oxide (ZnO) and aluminium-doped zinc oxide (ZnO:Al) as potentiometric pH sensors. The hydrothermal technique was used to grow ZnO and ZnO:Al thin film nanostructures with doping concentrations of 1, 3, and 5 at% Al on the cleaned ITO substrates. The pH potentiometric sensing was performed in a wide pH range of 4-12 and produced sensitivity, including stability of the nanostructures. The prepared samples were also characterized by X-ray diffraction analysis (XRD), field effect scanning electron microscope (FESEM), and energy dispersive X-ray (EDX) to explore the influence of aluminium concentration on structural and morphology characteristics and then prepared as electrodes for pH sensing. From the XRD result, the sharp peaks and high peak intensities demonstrated well crystalline of the synthesized ZnO nanorods. Furthermore, the FESEM shows the growth of array nanorods perpendicular over the surface of ITO. The sensitivity of the pH sensor with 3 at% ZnO:Al exhibits higher sensitivity (43.80 mV/pH) and larger linearity (0.9507).

Influence of Sputtering Pressure on the Conductivity and Transparency of Aluminum-Doped Zinc Oxide Films

Influence of Sputtering Pressure on the Conductivity and Transparency of Aluminum-Doped Zinc Oxide Films

Evaluation of thermal stresses on thin Al and AZO films deposited on polyethylene terephthalate substrates for flexible electronics applications

Thin aluminum (Al) films are widely used in electronic devices and flexible photovoltaics. In a similar capacity, Aluminum Doped Zinc Oxide (AZO) serves the same purpose. This study examines the sensitivity of both films to thermal stresses when sputtered onto Polyethylene Terephthalate substrates. These stresses include a constant temperature of 100 °C and temperature fluctuations ranging from 0 °C to 100 °C. The resistance of the films was affected by isothermal aging, but not by thermal cycling. Interestingly, thermal cycling led to microcracks in the film, while isothermal aging resulted in a slight increase in bonding and oxygen content in the Al films. For AZO films, imaging did not reveal any noticeable changes in morphology. However, both thermal cycling and isothermal aging led to a minor increase in the resistance of AZO films. These findings highlight the pronounced impact of thermal stress on the performance and structural integrity of both thin films.

Effects of TiO2 thin films on silicon nanowire arrays in heterojunction solar cells

In recent years, the energy crisis has gained increasing attention, with greater emphasis being placed on renewable energy. Currently, solar power is regarded as the most developed form of renewable energy. Many materials have been used in solar cells. Radiofrequency (RF) magnetron sputtering is an effective technique used to produce large-area, easy-to-process thin films. In this study, we fabricated p-layer silicon nanowire (SiNW) arrays by using electroless etching to replace previous multilayer films. TiO2-SiNW array heterojunctions were fabricated by preparing TiO2 as an N layer through magnetron sputtering. Subsequently, the Grey–Taguchi method was used to analyze and optimize p–n heterojunctions with TiO2 films. After the effects of the sputtering parameters (RF power, process pressure, deposition temperature, and deposition time) on surface morphology, material structure, photoelectric conversion efficiency, and reflectivity were investigated, an aluminum-doped zinc oxide (AZO) window layer was added and annealed. Grey correlation analysis revealed a decrease in reflectivity from 8.02225 % to 7.72081 % and an increase in photoelectric conversion efficiency from 0.01915 % to 0.082 %. During the confirmation runs, the TiO2 film was found to be amorphous and wrapped around an array of SiNWs. After the AZO window layer was added, reflectivity increased to 18.04712 %, and the efficiency of photoelectric conversion increased to 0.124 %. In addition, according to the results of the confirmation runs, the AZO film was polymorphic. These experimental results confirm the effectiveness of RF magnetron sputtering, which provides high reflectivity and photoelectric conversion efficiency.

Epsilon-near-zero material-based bi-layer metamaterials for selective mid-infrared radiation

Selective mid-infrared (MIR) radiation is highly desirable in many applications. However, there are still great challenges to simultaneously achieve MIR camouflage and radiative cooling utilizing simple structure. This work theoretically and experimentally proposes a bi-layer metamaterial composed of aluminum doped zinc oxide (AZO) nanoparticles embedded in Al2O3 matrix on the aluminum film. The bi-layer metamaterial exhibits high performance in MIR camouflage with radiative cooling, a low emissivity ( = 0.11, = 0.20) in atmospheric windows and a high emissivity ( = 0.81) in non-atmospheric windows. The interaction of the epsilon-near-zero (ENZ) mode and localized surface plasmon resonance (LSPR) mode is responsible for the perfect emission over the wavelength range of 5–8 m. Additionally, the proposed selective MIR emitter supports large-angle incidence and has great polarization insensitivity. This demonstrates that epsilon-near-zero material-based bi-layer metamaterial is highly promising for the development of selective mid-infrared radiation.

Multifunctional Al-doped ZnO thin films for vertically aligned liquid crystal devices

The integration of ITO-free transparent conductive layers remains a big challenge for development of next generation technologies. Here, we demonstrate the feasibility of transparent and conductive Aluminum-doped Zinc Oxide (AZO) thin films to operate simultaneously as electrode and alignment layer in Liquid Crystal (LC) device configuration. Controlling the growth process of AZO thin films by Atomic Layer Deposition (ALD) technique results of predominantly (100) crystallographic oriented AZO with very high transparency and excellent conductivity. The exceptionally low surface free energy of (100) oriented AZO, along with the topological modification following the mechanical rubbing treatment were used to elucidate the mechanism of LC molecules alignment on the surface of AZO film. The uniform vertical orientation of the nematic LC director was confirmed by polarized optical microscopy and pretilt angle measurements. The competitive electro-optical performance in terms of phase modulation, threshold and saturation voltages and contrast ratio of the assembled LC device reveals the great potential of AZO thin films as transparent electrode and alignment layer for future LC display applications with versatile functionality.

Effects of Cyclic Bending Parameters on Aluminum-Doped Zinc Oxide Thin Films for Flexible Device Applications

Effects of Cyclic Bending Parameters on Aluminum-Doped Zinc Oxide Thin Films for Flexible Device Applications

Performance Signature of the Best Candidate-Graded Bandgap Materials for Solar Cells with Steady-State Conversion Efficiency

This is a comprehensive research endeavor focused on enhancing the efficiency of the proposed solar cell design. The integration of the simulation techniques, judicious material selection, and meticulous performance metrics showcase a methodical approach toward creating a solar cell capable of achieving high efficiency across a wide spectrum of light in the AM 1.5 G1 sun solar cell illumination spectrum. Having said this, many researchers are still working on the efficiency potential—based on external radiative efficiency (ERE), open-circuit voltage loss, and fill factor loss—of high-efficiency solar cells. The solar cell is built on aluminum-doped zinc oxide (ZnO) as a transparent conductive oxide layer; aluminum nitride (AlN) as the window layer (emitter); an SWCNT layer as the absorber layer; gallium phosphide (GaP) as the contact layer; and silicon as the substrate. The proposed solar cell transmission, reflection, and absorption relative to the variations in wavelength band spectrum are studied. The conduction and valence band energy diagrams of the solar cell design structure are simulated against the layer thickness variations for the suggested solar cell structure. Short-circuit current density and maximum power variations are clarified versus the bias voltage. Light current density is simulated versus the bias voltage (J/V characteristics curve) of the suggested solar cell design structure. The carrier generation–recombination rate is also simulated by the COMSOL simulation program versus the layer thickness of the suggested solar cell structure. The solar cell circuit design has a fill factor (FF) value of 74.31% and a power conversion efficiency value of 29.91%.

Enhanced photocatalytic and antimicrobial properties of undoped and aluminum-doped zinc oxide nanosheets synthesized via novel laser-assisted chemical bath technique

Enhanced photocatalytic and antimicrobial properties of undoped and aluminum-doped zinc oxide nanosheets synthesized via novel laser-assisted chemical bath technique

Comparison of the Optical Properties of Different Dielectric Materials (SnO2, ZnO, AZO, or SiAlNx) Used in Silver-Based Low-Emissivity Coatings

This work analyzed and compared the optical and photoenergetic properties of low-emissivity coatings made from various dielectric materials deposited through magnetron sputtering following a systematic, comparable method. Different multilayer structures of silver-based low-emissivity coatings were studied using SnO2, ZnO, SiAlNx, and aluminum-doped zinc oxide (AZO, which is inherently a semiconductor, but it fulfils an optical dielectric function in this type of structure). The properties of the coatings were determined by spectrophotometric and sheet resistance measurements. Coatings with AZO as the dielectric layers obtain the best photoenergetic performance because silver growth is more efficient on AZO. We also studied the effect of ion bombardment on AZO and SiAlNx in an attempt to obtain a better low-emissivity coating, achieving better results when etching the dielectric layer with an ion gun. Regarding the structures’ visible transmission, the oxides produced better transmission results. Based on the above, we concluded that AZO had the best optical and photoenergetic properties in our deposition system, observing, in the best-case scenario, improvements in emissivity from 0.083 with SnO2 to 0.058 with AZO and to 0.052 using an ion beam on AZO and improvements in visible transmission from 81.9% with SnO2 to 86.8% with AZO.

Aluminum doped zinc oxide thin films with lower activation energy prepared by radio frequency magnetron sputtering

Aluminum doped zinc oxide thin films with lower activation energy prepared by radio frequency magnetron sputtering

Transparent conducting oxides (TCOs) based gratings for light absorption in near infrared spectrum

The present work examines the absorption enhancement of Transparent Conducting Oxides (e.g., Aluminum doped Zinc Oxide (AZO), Gallium doped Zinc Oxide (GZO), and Indium doped Tin Oxide (ITO) for widely used telecom spectral window around λ = 1550 nm. This is by virtue of the fact that the silica-based optical fiber exhibits minimum loss in this window. It is well established that one-dimensional metallic lamellar grating can significantly enhance light absorption through diffraction and excitation of surface plasmon polaritons (SPPs) at the metal-dielectric interface. This results in subwavelength confinement and hence, enhanced optical absorption in the absorbing layer near the grating. The absorption enhancement can be tuned in different spectral regions by controlling grating parameters, such as grating period, grating height, and grating aspect ratio. The present work focused on establishing Transparent Conducting Oxides (TCOs) as effective plasmonic materials for metallic grating to optimize optical absorption in the near-infrared (NIR) spectral region. The role of TCOs and the grating parameters in fine-tuning the optical absorption enhancement is investigated. Moreover, TCO grating-based designs optimized for absorption enhancement in and around the telecommunication wavelength are proposed.

Engineering the temporal dynamics of all-optical switching with fast and slow materials

All-optical switches control the amplitude, phase, and polarization of light using optical control pulses. They can operate at ultrafast timescales – essential for technology-driven applications like optical computing, and fundamental studies like time-reflection. Conventional all-optical switches have a fixed switching time, but this work demonstrates that the response-time can be controlled by selectively controlling the light-matter-interaction in so-called fast and slow materials. The bi-material switch has a nanosecond response when the probe interacts strongly with titanium nitride near its epsilon-near-zero (ENZ) wavelength. The response-time speeds up over two orders of magnitude with increasing probe-wavelength, as light’s interaction with the faster Aluminum-doped zinc oxide (AZO) increases, eventually reaching the picosecond-scale near AZO’s ENZ-regime. This scheme provides several additional degrees of freedom for switching time control, such as probe-polarization and incident angle, and the pump-wavelength. This approach could lead to new functionalities within key applications in multiband transmission, optical computing, and nonlinear optics.