Aluminum-doped Zinc Oxide Research Articles

Enhanced Optoelectronic Properties of Few-Layer Graphene for Transparent Conducting Electrode: Density Functional Theory Perspective

The challenge in utilizing graphene for transparent conducting electrodes (TCE) is to increase the electronic conductivity without significantly decreasing its transmittance. Forming a few-layer structure is an effective way to modify the electronic properties of graphene. In this paper, we used the density functional theory (DFT) method to study the effect of the number of few-layer graphene (FLG) layers on the electronic conductivity and transmittance. We find that increasing the number of layers leads to an increase in electronic conductivity. On the other hand, a decrease in transmittance was observed when the number of layers was increased. Based on the performance analysis, the optoelectronic properties of FLG with more than three layers were better than those of conventional TCE materials, such as indium tin oxide (ITO) and aluminium-doped zinc oxide (AZO). The calculated electronic conductivity and transmittance of a 4-layer FLG were 2.23×1019 (1/Ω.m.s) and 95.69%, respectively. This finding can be used as guidance for experimental research in developing graphene-based TCE materials. Keywords: density functional theory, electronic conductivity, few-layer graphene, transmittance

Preparation and properties of Cu2MgSnS4 thin films and fabrication of heterojunction devices

Abstract Copper based chalcogenides have garnered growing importance in the area of thin film photovoltaics. Cu2MgSnS4 (CMTS) is one of the newest materials in this family of materials. It is a p-type material which find multiple applications in the field of photovoltaics. Cu2MgSnS4 thin films were deposited onto soda lime glass substrates using automated vacuum spray pyrolysis technique at a substrate temperature of 300 °C and annealed at different temperatures from 300 °C to 375 °C in steps of 25°C. The structural, elemental, morphological, optical, and electrical properties of the material were studied. X-Ray Diffraction studies showed that annealing eliminates impurity phases and improves crystallinity. Field Emission Scanning Electron Microscopy studies showed improved grain size and uniform deposition of the films. The energy bandgap of the as-prepared film is 2.02 eV and that of annealed films are around 2.5 eV. Hall measurements show that the material exhibit p-type conductivity with high value of conductivity, mobility and bulk concentration. Heterojunction devices were fabricated with chemical bath deposited CdS as a buffer layer and spray deposited Aluminium doped Zinc Oxide (Al:ZnO) as n-layer. Silver contacts were placed as electrodes over the top layer. The fabricated device architecture is <FTO/AZO/CdS/CMTS/Ag>. The junction parameters including rectification ratio, knee voltage, series resistance and Ideality factor of all the devices are calculated. The device annealed at 375 °C showed an ideality factor of 2.23, which is the best among all the fabricated devices.

Thermal and rheological behavior of aluminium-doped zinc oxide nanofluids: Experimental study and application of artificial neural network model

In this study, the influence of Al-doping concentration on the thermal and rheological characteristics of pristine zinc oxide (ZnO) nanofluids was investigated across a range of temperatures and nanoparticle concentrations. A multilayer perceptron (MLP) artificial neural network (ANN) with an optimized topology was employed to model the thermal conductivity and viscosity of nanofluids. The addition of 0.13 M of Al-doped zinc oxide nanoparticles at 1 % rate led to a remarkable 64 % increase in the thermal conductivity of the base fluid (50:50 ratio water + ethylene glycol mixture). Furthermore, incorporating 1 % of these Al-doped nanoparticles outperformed pure zinc oxide, resulting in a 44 % boost in thermal conductivity. The enhanced heat transfer capabilities of Al-doped zinc oxide were evident across different doping and nanoparticle concentrations. The viscosity of nanofluids increases with an increase in nanoparticle concentration and decreases with an increase in temperature. ZnO and Al-doped ZnO nanoparticles have been prepared and studied their structural, morphological and elemental properties using XRD, SEM and EDS respectively. The predicted thermal and rheological behaviours are in close agreement with the experimental values.

Improvement in the performance of indium free dye sensitized solar cell by the use of polyaniline composite

The photovoltaic study of the fabricated dye sensitized solar cells is revealed in this paper. To provide indium free approach, fluorine doped tin oxide (FTO) and aluminium doped zinc oxide (AZO) glass substrate were used as charge collectors for counter electrodes and photoanode respectively. Also, a novel and natural mixed dye was used as sensitizer and mixture of doped polymer (polyaniline with metallic oxides of tin, vanadium and cerium) and iodide-triiodide couple was utilized as electrolyte for the cell. Optical band gap and light absorption performance of dyes were studied by ultraviolet-visible (UV-vis) spectroscopy. Surface morphology and elemental composition of polymer composites was studied using scanning electron microscopic (SEM) with energy dispersive X ray (EDX) analysis. Phase analysis of the composites was determined by X-ray diffraction and thermal behavior with the help of thermo gravimetric analysis (TGA). Photovoltaic characteristics (I-V) and induced photon to current efficiency (IPCE) measurements were also investigated. Highest IPCE of 17.7% was observed when polyaniline was doped with oxide of vanadium. Hence an efficient, green, indium free and novel cell is fabricated by the usage of different charge collector substrate, natural dye sensitizer and quasi solid-state electrolyte.

Design and simulation of highly efficient CZTS/CZTSSe based thin-film solar cell

Thin-film solar cells are a substitute for more common crystalline silicon solar cells, which consist of thin semiconductor layers. Thin-film materials comprise direct bandgap and can absorb sunlight more efficiently than silicon. In this article, a double-absorber-based thin-film solar cell comprising CZTS/CZTSSe is designed and optimized through numerical simulation. The proposed solar cell structure consists of a transparent window layer made of aluminum-doped zinc oxide, followed by an intrinsic zinc oxide layer, an n-type cadmium sulfide layer, and a p-type combined absorber layer of copper zinc tin sulfide (Cu2ZnSnS4) (CZTS) and copper zinc tin sulfur-selenium alloy (Cu2ZnSn(S,Se4)) (CZTSSe). The structure is further optimized by introducing two interfacial layers between CZTSSe/CZTS and CZTS/CdS. The highest conversion efficiency is achieved by adjusting the thicknesses of the layers, the doping densities in different layers, and the defect densities in the two absorber layers. The optimized model, with a total thickness of 2.01 μm, demonstrates an open-circuit voltage (Voc) of 0.7669 V, a short-circuit current (Jsc) of 48.57740 mA/cm2, a fill factor (FF) of 70.61%, and efficiency (η) of 26.31%. These results suggest that CZTS is a promising candidate for replacing other thin-film photovoltaic materials, such as CdTe. The proposed double-absorber thin-film solar cell optimizes doping concentration, thickness, and defect density to enhance performance metrics and efficiency while utilizing non-toxic materials to promote cost-effective, environmentally friendly energy solutions.

Theoretical improvement of the energy conversion efficiency of an AZO/CdTe heterojunction solar cell to over 27% by incorporating FeSi2 as a second absorber layer

Abstract This paper presents the numerical analysis of cadmium telluride (CdTe) based solar cells using iron di silicide (FeSi2) as the second absorber layer and aluminum-doped zinc oxide (AZO) as the window layer. The photovoltaic performance of solar cells with Al/AZO/CdTe/FeSi2/Ni structure was analyzed and improved by SCAPS-1D software. When analyzing the influence of thickness and carrier concentration on the photovoltaic performance, it was found that the optimum values for the CdTe layer were 300 nm and 1015 cm-3, for the AZO layer they were 10 nm and 1018 cm-3, while for the FeSi2 layer they were 1 µm and 1018 cm-3. The defect density (Nt) at the AZO/CdTe and CdTe/FeSi2 interfaces was also analyzed, obtaining that the optimum value of Nt is 1010 cm-2 at both interfaces. Device optimization is achieved by obtaining a maximum Power Conversion Efficiency (PCE) of 27.22% with an open circuit voltage (Voc) of 0.63 V, a short circuit current density (Jsc) of 51.43 mA/cm2 and a fill factor (FF) of 83.06%, which makes FeSi2 a potential alternative for the development of CdTe-based solar cells due to its absorption of photons with lower energy wavelengths.

A semi-transparent thermoelectric glazing nanogenerator with aluminium doped zinc oxide and copper iodide thin films

To address the pressing need for reducing building energy consumption and combating climate change, thermoelectric glazing (TEGZ) presents a promising solution. This technology harnesses waste heat from buildings and converts it into electricity, while maintaining comfortable indoor temperatures. Here, we developed a TEGZ using cost-effective materials, specifically aluminium-doped zinc oxide (AZO) and copper iodide (CuI). Both AZO and CuI exhibit a high figure of merit (ZT), a key indicator of thermoelectric efficiency, with values of 1.37 and 0.72, respectively, at 340 K, demonstrating their strong potential for efficient heat-to-electricity conversion. Additionally, we fabricated an AZO-CuI based TEGZ prototype (5 × 5 cm²), incorporating eight nanogenerators, each producing 32 nW at 340 K. Early testing of the prototype showed a notable temperature differential of 22.5 °C between the outer and inner surfaces of the window glazing. These results suggest TEGZ could advance building energy efficiency, offering a futuristic approach to sustainable build environment.

Study on UV-VIS characteristics of Aluminum Zinc Oxide nanoparticles through manganese substitution using Wemple-Di domenico method and diffuse reflectance spectroscopy

In this research Manganese-substitution impact on linear and nonlinear (NL) optical properties of Aluminum-doped ZnO (AlZnO) Nanoparticles (NPs) are investigated. Utilizing measured data of reflectance acquired from the DRS, the higher-order NL optical characteristics of the provided NPs are examined. The maximum quantity of NL susceptibility χ3 is measured to be around 3.945 × 10−10 esu at wavelength λ = 520 nm and 7.467 × 10−11 esu at wavelength λ = 530 nm for AlZnO and Manganese-substituted Aluminum-doped Zinc-Oxide (Mn-also) NPs, for particle sizes 14−67 nm and 11−54 nm, consecutively. Consequently, the synthesis method (sol–gel) which is used in this work concluded a decrease in particle size and different optical behavior especially in UV spectral regions during the substitution with Manganese in comparison with the AlZnO. This decrement assures that a decrease in the size of crystallite induces a decline in the χ3. The obtained optical parameters are red shifted with the Manganese substitution. Also, the NL absorption coefficient (β c(m/W)) is enhanced in the UV range. The maximum of the NL absorption coefficient (β c(m/W)), for AlZnO and Mn-AlZnO NPs, are determined (at λ = 250 nm) 2.24 × 10−18 (m/W) and 5.76 × 10−15 (m/W) respectively.

Aluminum doped zinc oxide as UV laser-based nanothermometer

Abstract This work explores thermal laser-based sensor capabilities utilising random lasing emission obtained from zinc oxide (ZnO) nanorods prepared by chemical bath deposition. The ZnO nanorods were doped with Aluminum (Al) at a concentration of 10 mM by using a simple dip method for several dip durations of 20 s, 30 s, 40 s, 60 s and 80 s, respectively. In our previous work, we successfully observed random lasing emission. Building on these findings, this work delves deeper into the thermal sensitivity of nanorod structure at room temperature within the ultraviolet (UV) range. The highest thermal sensitivity of 0.001 °C-1 was obtained from Al-doped ZnO nanorods that were dipped for 60 s. The lasing threshold was 22.92 mJ/cm2 and the lasing spectral width was 1.16 nm.

Aluminum's role in tailoring the characteristics of room temperature co-sputtered gadolinium and aluminum-doped ZnO thin films

This study investigated the characteristics of gadolinium (Gd) and aluminum (Al) co-doped ZnO synthesized by co-sputtering at varying concentrations of Al. FESEM images revealed a morphology containing spherical-hexagonal nanostructures of different sizes based on the amount of Al. The EDS spectra clearly demonstrated the presence of Al, Gd, Zn, and O, confirming the successful incorporation of Gd and Al ions into the ZnO lattice in agreement with XRD profiles, not detecting any secondary phases. The photoluminescence study revealed that doping-induced defect states (oxygen vacancies, zinc vacancies, and zinc interstitial) were responsible for the many characteristic peaks of deep level emission observed in the photoluminescence spectra. Higher Al doping induced changes in magnetic characteristics as reflected in the greater root mean square value (δfrms), and the root mean square phase shift value (Φrms) in MFM analysis, whereas the magnetic correlation length (L) decreases. The incorporation of Al at higher concentrations into Gd-doped ZnO resulted in improved magnetic behavior suggesting the exchange interaction between Gd and Al ions mediated by oxygen vacancies. These results confirm that sufficient Al doping can efficiently improve the properties and magnetic behavior of ZnO-based DMS systems, which could potentially pave the way towards the realization of spin and/or optical based electronic devices.

Efficient Silicon Solar Cells with Aluminum‐Doped Zinc Oxide‐Based Passivating Contact

AbstractCrystalline silicon (c‐Si) solar cells require passivating contacts to unlock their full efficiency potential. For this doped silicon layers are the materials of choice, as they yield device voltages close to the thermodynamic limit. Yet, replacing such layers with wide‐bandgap metal oxides may be advantageous from a cost perspective and minimize parasitic optical absorption. Here the aluminum‐doped zinc oxide (AZO)‐based passivating contacts with high electron selectivity are presented. The SiO2/AZO/Al2O3 stack is demonstrated to provide excellent surface passivation on c‐Si (implied Voc up to 742 mV) after thermal annealing, and an average contact resistivity of 51 mΩ cm2 is simultaneously obtained after etching off Al2O3 capping layer. By the implementation of AZO‐based electron‐selective contact, a champion power conversion efficiency (PCE) of 24.3% is achieved on c‐Si solar cells, representing the PCE record for metal oxide‐based passivating contacts. Finally, the efficiency potential, cost, and industrial compatibility of the AZO‐based electron‐selective contacts are discussed, paving the way for industrial applications.

Investigation of dual plasmonic material integrated wrench-shaped PCF sensor with broadband resonance for cancer cell & chemical detection

In this work, a unique Photonic Crystal Fiber based on the Localized Surface Plasmon Resonance is designed for cancer cell and chemical detection. A novel combination of plasmonic materials namely Aluminum doped Zinc Oxide (AZO) and a Silver (Ag)-TiO2 bilayer is deposited along two horizontal slits to achieve resonance at two separate wavelengths within a particular refractive index. The sensor achieves resonance at different wavelengths along x and y polarizations, broadening analyte detection for a specific RI. Two modes of operation are introduced: mode-1 is optimized to achieve the highest Amplitude Sensitivity (AS), and mode-2 to maximize the Wavelength Sensitivity (WS). The mode-1 is examined for a range of RI from 1.35 to 1.42, while the other is 1.35–1.41. The sensor can showcase an AS of 4641.51 RIU−1 for Ag at RI 1.36, which is the highest value of AS found in literature when Ag is used as plasmonic material, while AZO achieves a high AS of 3204.51 RIU−1 at 1.41 RI. A highest WS of 10,320 and a Double Peak Shift Sensitivity (DPSS) of 8089.5 nm/RIU at 1.41 RI is obtained using the mode-2 configuration with a wavelength resolution of 9.69 × 10−6 RIU and a maximum FOM of 568.22 RIU−1. The sensor is examined to investigate skin, cervical, and blood cancer by analyzing the Basal, HeLa, and Jurkat cells, which yielded superior outcomes when detected using AS among relevant works. In addition, the detection of various industrial chemicals like acetone, hexane, isopropanol, and ethanol is also manifested in this study.

Synthesis, Characterization, and Evaluation of the Antimicrobial and Anticancer Activities of Zinc Oxide and Aluminum-Doped Zinc Oxide Nanocomposites.

In this research, we developed undoped and aluminum-doped zinc oxide for antimicrobial and anticancer activities. This study focuses on the synthesis, characterization, and biological activities of zinc oxide nanoparticles (ZnO NPs) and aluminum-doped zinc oxide nanocomposites (Zn1-xAlxO NCs) at varying concentrations (x = 0, 0.25, 0.5, and 0.75 wt%) using the coprecipitation method. Various characterization techniques such as XRD, UV-Vis, FTIR, EDX, and SEM were performed to analyze the crystal structure, optical properties, functional group identification, elemental composition, and surface morphology. The antimicrobial activity test showed that Zn0.75Al0.25O NCs exhibited the strongest inhibition zone against Bacillus cereus compared to Staphylococcus aureus > Pasteurella multocida > Escherichia coli. Moreover, the cytotoxicity and cell viability of liver cancer (HepG-2), breast cancer (MCF-7), ovarian cancer (SKOV3), and normal liver cell lines) were evaluated using the MTT assay, demonstrating that Zn0.75Al0.25O NCs not only enhance cell destruction but also show low cytotoxicity and high biocompatibility at low concentrations. These results suggest that Zn0.75Al0.25O NCs could be a promising candidate for in vivo anticancer applications and should be further investigated.

Low-Cost, High-Efficiency Aluminum Zinc Oxide Synaptic Transistors: Blue LED Stimulation for Enhanced Neuromorphic Computing Applications.

Neuromorphic devices are electronic devices that mimic the information processing methods of neurons and synapses, enabling them to perform multiple tasks simultaneously with low power consumption and exhibit learning ability. However, their large-scale production and efficient operation remain a challenge. Herein, we fabricated an aluminum-doped zinc oxide (AZO) synaptic transistor via solution-based spin-coating. The transistor is characterized by low production costs and high performance. It demonstrates high responsiveness under UV laser illumination. In addition, it exhibits effective synaptic behaviors under blue LED illumination, indicating high-efficiency operation. The paired-pulse facilitation (PPF) index measured from optical stimulus modulation was 179.6%, indicating strong synaptic connectivity and effective neural communication and processing. Furthermore, by modulating the blue LED light pulse frequency, an excitatory postsynaptic current gain of 4.3 was achieved, demonstrating efficient neuromorphic functionality. This study shows that AZO synaptic transistors are promising candidates for artificial synaptic devices.

Simple and hybrid metalens with high polarization conversion efficiency for near-infrared spectrum

Thanks to their ability to control light, research on metalenses is developing rapidly. However, it is still quite difficult to design broadband metalenses with high polarization conversion efficiency. In this study, an alternative plasmonic material, aluminum-doped zinc oxide, is presented for metalens operating in near-infrared regime. We propose simple and hybrid metalenses with high polarization conversion efficiency and high transmission values that can focus efficiently in a wide near-infrared bandwidth (700–1000 nm). We design metalens consisting of subwavelength aluminum-doped zinc oxide nanoblocks based the Pancharatnam-Berry phase method and utilizing the finite-difference time-domain method. The polarization conversion efficiency (minimum 87 %) and transmission values (minimum 85 %) calculated for the metalens unit cell are higher than those previously obtained over the entire 300 nm bandwidth. In addition, we propose hybrid metalens to focus the incident beam in right and left handed circular polarized states in the studied frequency range. The presented aluminum-doped zinc oxide metalens with high polarization conversion efficiency and transmission values can find a place in the applications of near-infrared nanophotonic systems.

Effect of the annealing temperature on the refractive index and extinction coefficient of aluminum-doped zinc oxide: a low-cost electron transport layer

Effect of the annealing temperature on the refractive index and extinction coefficient of aluminum-doped zinc oxide: a low-cost electron transport layer

Gas sensing beyond classification: Analysis of gas mixtures using multisensor array based on Al-doped zinc oxide

Understanding the composition of gas mixtures is still a primary prerogative of complex analytical units or biological olfaction systems. Attempts to mimic the olfactory processes by using a multisensor array combined with machine learning algorithms led mainly to solving a problem of a selective classification of odors or regression over the range of concentrations of the same odor. The identification of individual analytes in a mixture remains a difficult task. In this study, we test the identification of individual chemicals in the composition of the gas mixture with a feature extraction algorithm using a multisensor array based on aluminum-doped zinc oxide. Our approach is based on matching the selected parameters of the response curves which share considerable similarity if a volatile compound is common in any two mixture combinations. We demonstrate the efficiency of the method by analyzing five analytes such as acetone, benzene, methanol, ethanol, and isopropanol, and their mixtures. As a result, we were able to efficiently classify all 31 odors with an accuracy of about 99%. We have achieved the mean values of F1 scores of 0.52, 0.63, and 0.59 reaching up to 0.80–0.86 for the prediction of every individual analyte in 2-, 3- and 4-component gas mixtures, respectively. While using just raw signals at steady state, we found that the results become rather biased as the number of analytes increases in a mixture. Thus, our approach enables an improved, more accurate, and thorough examination of the gas mixtures, expanding the scope of application of multisensor systems beyond the common “classification” tasks.

Impacts of ultraviolet absorption by zinc oxide nanoparticle modifiers on asphalt aging

Ultraviolet absorption ability of modifiers is essential to protect asphalt from ageing. However, the detailed correlation between them remains unclear. In this study, zinc oxide nanoparticles were used as modifiers, and their ultraviolet absorption ability was manipulated by magnesium and aluminum doping. The influence of ultraviolet absorption ability of the nanoparticles on asphalt ultraviolet ageing was investigated experimentally, and their correlation was revealed in detail by curve fitting. The results show that aluminum doping enhances the ultraviolet absorption ability of nanoparticles, leading to superior anti-aging performance in aluminum-doped zinc oxide modified asphalt compared to pure zinc oxide. Conversely, magnesium doping shows a contrary modification. Evaluating the ultraviolet absorption ability of nanoparticle modifiers by bandgap and absorption intensity, we found that softening point increments, viscosity ageing index, and sulfoxide index exhibit a decreasing trend mainly in the bandgap range of 3.269 to 3.334 eV, whereas carbonyl index shows a decreasing trend mainly in the lower bandgap range of 3.183 to 3.269 eV. This phenomenon is primarily due to the different reactivity of carbon and sulfur with oxygen in asphalt. Curve fitting analysis revealed an exponential correlation between the ageing index of asphalt and the ultraviolet absorption ability of nanoparticles. To achieve superior anti-ultraviolet ageing performance, the nanoparticles should possess an absorption intensity above 0.961 a.u. and a bandgap below 3.299 eV. Moreover, stronger ultraviolet absorption ability of nanoparticles is needed to prevent the formation of carbonyl compounds. The underlying correlation established in the present work has significant implications for selecting suitable modifiers to prevent ultraviolet ageing of asphalt.

An improved supply of anthocyanin dye for creation of effective dye-sensitized solar cells grounded on natural dyes

Abstract In order to advance the power conversion efficiency of dye-sensitized solar cells, this article shows the selection of better sources of the sensitizer anthocyanin. The cells were created by combining liquid and solid electrolytes, adding natural dye, and employing a photo anode of aluminium-doped zinc oxide and a counter electrode of fluorine-doped tin oxide. Light harvesting efficiency, scanning electron microscopy, ultraviolet and infrared spectroscopy, and other methods were used to characterise the cells. From all the combinations made utilising different sources, the cell based on the D1 dye sample from Hibiscus sabdariffa L. (Manipur) had the best efficiency at 1.58 %. An effective DSSC was the end result of this strategy for identifying the optimal extraction source for anthocyanin natural dyes.

Influence of power ramps on the physical properties of AZO thin films deposited at room temperature by RF magnetron sputtering technique

Abstract Aluminum-doped zinc oxide (AZO) thin films were deposited on glass substrates at room temperature by RF sputtering technique. Power ramps between 125 and 105 W were applied with a step of 4 W by intervals of 15, 7.5 and 1.8 min, for 180 min at 1.60 Pa. In this study, we investigated the structural, morphological, electrical, and optical properties of AZO films. X-ray Diffraction analysis showed that the films have a wurtzite-type hexagonal crystalline structure with a preferential crystallographic orientation (002) normal to the c axis. The average transmittance is greater than 76% for the wavelength range in the visible spectrum. The bandgap values were found between 3.32 and 4.01 eV, and refractive index was 1.79–2.60. Atomic force microscope measurements show homogeneous films with a roughness between 17–22 nm. A minimum resistivity value of 2.0 × 10−3 Ω cm was obtained for the film by using a power ramp of 4 W/1.8 min.