Al Co-doping Research Articles

Investigating the influence of the Ag and Al co-doping in ZnO electron transport layer on the performance of organic-inorganic perovskite solar cells using experimentation and SCAPS-1D simulation

The sufficient material selection of electron transport layer (ETL) enormously promises exceptional conversion efficiency from perovskite (PVT) solar cells (PSCs), which in turn give rise to their rapid establishment in world-wide photovoltaic (PV) market. Among the tactics exerted on ETLs, and thus, intensifies the adequacy of associated PSCs, the methodology of doping stands productive. Therefore, this research validates the implementation of such effectual ETLs on widely approved methyl ammonium lead triiodide (MAPbI3)–based PSCs. The work brings together two versions of zinc oxide (ZnO) ETLs: one in its pristine form, and the other is aluminum (Al) co-doped with silver (Ag) represented as Ag-AZO. The investigation launches the PV capabilities of Ag-AZO ETL against its undoped correspondent. Accordingly, the earlier part of the investigation centers on the experimental assessment of ZnO and Ag-AZO nanoparticles (NPs) affirming their material and morphological aspects. Later, the research deals with the involvement of both NPs as ETLs signifying the PV potential of MAPbI3–based PSCs through comprehensive numerical analysis. The judgements of investigation declare that MAPbI3–based PSC with Ag-AZO ETL yields a desirable power conversion efficiency (PCE) of 27.26% against 25.98% from control cell. The investigation will definitely enlighten the development of forthcoming efficient PSCs incorporated with appropriate multiple metals co-doped ETLs.

Gamma irradiation-induced enhancement of Pb-related near-infrared luminescence in PbS/Al co-doped silica fiber

The impact of Al co-doping and gamma irradiation (0.3-3 kGy) on the spectral properties of lead-related active centers (PACs) in PbS/Al co-doped silica fiber (PADF) has been studied. Distinct absorption peaks at 700 and 1030 nm, and photoluminescence at 1100 nm, originated from Al-related lead active center (PAC-Al). The luminescence intensity of PACs at 900 and 1150 nm increased with irradiation doses in PADF with 0.01 at% Al co-doping. Notably, after irradiation with a 0.5 kGy dose, over a 16 dB enhancement of luminescence from PAC-Al was observed in PADF doped with 0.1 at% Al under 980 nm pumping. The on-off gain of the PADF at 1100 nm increased ∼12 dB after irradiation with a dose of 0.3 kGy. It was found that PAC-Al was preferentially generated over PAC at 1150 nm in Al co-doped fibers under irradiation. The proposed underlying mechanism for photoluminescence enhancement is the irradiation-induced reduction of Pb ions and Al-related defects. PbS/Al co-doped silica fiber is a promising candidate for active fibers operating at ∼1100 nm.

Synergistic effects of Al and Co co-doping on structural, electrical and luminescence properties of gallium ferrites synthesized by sol-gel method

Synergistic effects of Al and Co co-doping on structural, electrical and luminescence properties of gallium ferrites synthesized by sol-gel method

Narrowing Band Gap of Zno Codoping (Al+Mn) as a Photocatalyst Candidate for Degraded Textile Dye Wastewater

Photocatalyst degradation is one method to reduce industrial textile dye pollution in water. In this study, ZnO material has been synthesized by codoping Al and Mn by chemical coprecipitation method to determine the structural properties and optical properties of the material. From this research, it was found that the structure of ZnO after codoping Al and Mn did not change the hexagonal wurtzite phase but changes in other lattice parameters. The addition of Mn and Al codoping is reported to affect the intensity of XRD peaks, especially on the 101 lattice. The higher the scattering peak, the more angular the shift, indicating the magnitude of oxygen vacancies. The reflectance confirms this result that increasing Mn concentration decreases the energy gap to 3.258 eV. From these structural properties and energy gap values, ZnO codoping Al and Mn materials can be included in candidate materials that can be used as photodegradation agents for textile dyes.

Wedge-shape Al and Mg co-doped zinc oxide thin films: A Facile Route to achieve high thermoelectric power factor

Thin film thermoelectric technology has immense potential to become a next-generation power source for small-scale electronics. However, the rapid development of thin film thermoelectric still lacks a controllable structural design to improve the performance of thermoelectric devices for required temperature applications. This work presented a controlled thermoelectric design of ZnO-based thin films by Al and Mg co-doping using ALD. Herein, the Mg-doped ZnO sample exhibits the highest Seebeck coefficient of −311.83 μVK−1 at 500oC, while the maximum thermoelectric power factor of 3.68 μWcm−1K−2 is obtained at 300oC, which drops for higher temperatures. This decrease in power factor resulted from the reduction in electrical conductivity above 300oC. Similarly, the Al and Mg co-doped ZnO sample (Mg/Al ≈2 at%) exhibits a high thermoelectric power factor of 3.85 μWcm−1K−2 for ZnO based material due to its moderate electrical conductivity and Seebeck coefficient value at 325oC and behave monotonically for elevated temperatures. Scanning electron microscope (SEM) images show the formation of wedge-shaped structures for Al-incorporated samples, which helps to boost the overall thermoelectric performance. Additionally, we performed XRD, UV–Vis, Hall, and AFM analysis to get a deep insight into structural, optical, electrical, and surface features of the grown thin films and their linkage with the thermoelectric properties.

Effects of Nd and Al co-doping on the microstructure and lithium-ion transport in Li7La3Zr2O12 solid-state batteries

In this study, we synthesized co-doped Li6.25Al0.25La3-yNdyZr2O12 (LALNZO) solid-state electrolytes with varying Nd contents to investigate the influence Nd plays on phase evolution, microstructure, and lithium-ion conductivity. It was found that incorporating Nd ions into the lattice reduced bulk resistance by controlling Li+ concentration. However, X-ray diffraction analysis revealed that excessive Nd content led to the formation of Nd2O3, which negatively impacted ion transport and increased grain boundary resistance. It is noteworthy that the LALNZO (y = 0.2) ceramic exhibited outstanding performance, with 94% relative density, and ionic conductivity of 4.7 × 10−4 S/cm. The activation energy was 0.32 eV. Further, Li6.25Al0.25La2.8Nd0.2Zr2O12 was able to demonstrate a stable capacity of 103 mA.h. g−1 after 50 cycles at a current density of 0.1C when used as an electrolyte in lithium-ion batteries. The findings of this study provide valuable insights for developing advanced solid-state electrolytes for lithium-ion batteries.

Induced ferromagnetism in Ni(II) doped ZnO monolayers via Al co-doping and their optical characteristics: ab initio study

For applications in magneto-electronic devices, diluted magnetic semiconductors (DMSs) usually exhibit spin-dependent coupling and induced ferromagnetism at high Curie temperatures. The processes behind the behavior of optical emission and ferromagnetism, which can be identified by complicated microstructural and chemical characteristics, are still not well understood. In this study, the impact of Al co-doping on the electronic, optical, and magnetic properties of Ni(II) doped ZnO monolayers has been investigated using first principles calculations. Ferromagnetism in the co-doped monolayer is mainly triggered by the exchange coupling between the electrons provided by Al co-doping and Ni(II)-d states; therefore, the estimated Curie temperature is greater than room temperature. The spin–spin couplings in mono-doped and co-doped monolayers were explained using the band-coupling mechanism. Based on the optical study, we observed that the Ni-related absorption peak occurred at 2.13–2.17 eV, showing a redshift as Ni concentrations increased. The FM coupling between Ni ions in the co-doped monolayer may be responsible for the reduction in the fundamental band gap seen with Al co-doping. We observed peaks in the near IR and visible regions of the co-doped monolayer, which improve the optoelectronic device’s photovoltaic performance. Additionally, the correlation between optical characteristics and spin–spin couplings has been studied. We found that the Ni(II)’s d–d transition bands or fundamental band gap in the near configuration undergoes a significant shift in response to AFM and FM coupling, whereas in the far configuration, they have a negligible shift due to the paramagnetic behavior of the Ni ions. These findings suggest that the magnetic coupling in DMS may be utilized for controlling the optical characteristics.

Substitutional and interstitial atoms co-doping overcomes the strength–ductility trade-off in lightweight refractory medium-entropy alloys

Interstitial or substitutional solid solution strengthening is a common method for enhancing material mechanical properties, however, it is unclear whether their synergy can lead to better mechanical properties in materials. Here, we have demonstrated that the synergy of interstitial and substitutional elements can overcome the strength-ductility trade-off, which was substantiated in an O and Al co-doping (TiZrNb)94.5O0.5Al5 (O0.5Al5) lightweight refractory medium-entropy alloy (LRMEA) with a density ∼6.0 g/cm3. The co-doping LRMEA exhibits a simultaneous enhancement in strength and ductility with a yield strength of ∼1025 MPa and a fracture elongation of ∼35%, compared with the O or Al single doped alloys, i.e. (TiZrNb)99.5O0.5 (O0.5) and (TiZrNb)95Al5 (Al5). This combined increase in strength and ductility was attributed to synergistic interstitial and substitutional solid solution strengthening and the modification of dislocation motion mode from planar slip delocalization to a relatively diffuse, three-dimensional dislocation pattern, effectively alleviating stress concentration. This work provides valuable insight into the development of high-performance lightweight alloys.

Insights into the consequence of (Al–Zn) dual-doping on structural, morphological, and optoelectrical properties of CdO thin films

The present study explores the structural, morphological, optical, and electrical properties of spray pyrolyzed (Al–Zn) dual-doped CdO thin films. The un-doped and (Al–Zn) dual-doped CdO thin films have been deposited on glass substrate using spray pyrolysis route at 325 °C. The physical properties of the doped samples were analyzed as a function of Zn concentration (2–5 mol%) with constant Al (3 mol%) concentration. XRD analysis confirms the successful incorporation of (Al–Zn) dual-doping into CdO crystal as well as the polycrystalline nature was evident. No phase transitions were apparent from XRD data while revealing the single cubic structure of all the samples. The surface morphology of the samples studied by SEM. It shows the formation of rock-shaped microstructure and the variation of grain size with doping concentrations. Optical analysis was done using UV–vis spectroscopy within the range of 300–1200 nm. Maximum value of transmittance was attained for 3% (Zn–Al)-doped CdO sample. The dual doping exhibits the broadening of band gap values (2.61–3.84 eV) whereas a decrease in extinction coefficient was noticed as a function of Zn doping concentration. Electrical analysis was done using the four-probe method and a high resistivity was seen for higher Zn concentration. Obtained results and precise comparison with some similar films suggested that 2% Zn and 3% Al co-doping can be a suitable candidate for optoelectronic devices.

Electronic, magnetic and optical properties of Co(II) doped and (Al, Co) co-doped CdS nanowires: An ab initio study

In this work, we have carried out first-principles calculations for understanding the optoelectronic and magnetic properties of Co(II)-doped and (Al, Co) co-doped CdS nanowires. In the free carrier Co(II)-doped CdS NW, the spin-down Co(II)-ta state is completely empty, leading to a super-exchange process. The exchange coupling of the electron carrier (provided by Al co-doping) with the spin-down Co(II)-ta state promote a ferromagnetic ordering via double exchange interactions with a Curie temperature above room temperature. From the optical analysis, we found that Co(II) doping causes a blue-shift of the fundamental energy gap of CdS nanowire. The observed d-d spin-allowed transition peak of the Co(II) ion at 1.97 eV in the visible region is consistent with the experiments. The n-type Al co-doping not only generates an exciton-magnetic polaron (EMP) peak next to the fundamental bandgap but also exhibits the red-shift of the fundamental energy gap and Co(II)'s d-level-to-d-level transition bands. The correlation between spin-spin interaction and optical absorption shows that the d-d spin-allowed transition and optical energy gap both exhibit a blue-shift (red-shift) in the AFM (FM), supporting the experimental observation. Due to the paramagnetic behavior of the Co ions in the far configuration, there is no shift in the d-d transition peak or optical bandgap in the AFM and FM.

Synergetic effect of Bi and Al co-doping in GeTe-based thermoelectric materials leading to optimized carrier concentration tuning and high ZT

Improving the performance of thermoelectric (TE) materials that can convert waste heat into electricity is becoming increasingly important. Accordingly, the dimensionless figure of merit, ZT needs to be increased. Al, a group-III element, has not been widely used as a dopant in GeTe-based thermoelectric materials because it acts as a p-type dopant and thus further increases the hole carrier concentration of GeTe, which has already a high intrinsic hole concentration due to inherent Ge vacancies. Therefore, Al as a dopant in GeTe has been considered to have detrimental effects on the resulting thermoelectric performance. In this study, we aim to enhance the suitability of Al doping in GeTe-based materials through synergistically co-doping it with Bi. In this case, co-doping Al and Bi optimizes the carrier concentration and induces a high Seebeck coefficient from an additional increased effective mass and low total thermal conductivity arising from the numerous phonons scattering centers and decreased electronic contribution to heat transport. Consequently, a maximum ZT of ∼1.95 at 673 K with an increased average ZT is achieved. These results indicate that the p-type dopant Al, co-doped with Bi in GeTe-based thermoelectric materials is one of the very effective dopants which can eventually improve the overall TE performance of these materials for useful waste heat recovery application and cooling.

Boosting high-rate capacity and long-cycle stability of spinel LiMn2O4 by the Cr[sbnd]Al co-doping strategy

Jahn-Teller distortion and Mn dissolution are easily generated at a high current density, whilst hindering the elevation of high-rate capacity and long-cycle performance of spinel LiMn2O4. Herein, a CrAl co-doping strategy is proposed for preparing a series of LiCr0.04AlxMn1.96-xO4 (0 ≤ x ≤ 0.08) cathode materials using facile solid-state combustion. Crystalline structure and particle morphology are regulated by changing the Al-doping contents. After optimizing the Al-doping, the LiCr0.04Al0.01Mn1.95O4 cathode shows a unique truncated octahedron with the preferred growth of {111} crystal surfaces, which is conducive to reducing the Mn dissolution. Meanwhile, the LiCr0.04Al0.01Mn1.95O4 also exhibits a relatively high Mn average valence (+3.53) and lattice shrinkage, which can stabilize the spinel structure of the LiMn2O4 by inhibiting the Jahn-Teller to improve the electrochemical performance. Therefore, the optimized LiCr0.04Al0.01Mn1.95O4 cathode delivers the high-rate discharge capacity of 103.0 mAh/g and maintains the capacity retention of 67.0 % after 2000 cycles at 10C. Even at an ultra-high current rate of 30C, a long cycle life with a capacity retention of 78.0 % is also obtained after 1000 cycles.

Charge transfer and X-ray absorption investigations in aluminium and copper co-doped zinc oxide nanostructure for perovskite solar cell electrodes

This study explores influence of charge transfer and X-ray absorption characteristics in aluminum (Al) and copper (Cu) co-doped zinc oxide (ZnO) nanostructures for perovskite solar cell electrodes. Sol-gel technique was employed to synthesize the nanostructures, and their optical and morphological properties were investigated. X-ray diffraction (XRD) analysis confirmed high crystallinity and also single-phase composition of all the samples, particularly up to 5% Al co-doping. Field emission scanning electron microscopy (FESEM) exhibited the formation of pseudo-hexagonal wurtzite nanostructure and the transition to nanorods at 5% Al co-doping. Diffuse reflectance spectroscopy indicated a reduction in the optical band gap of co-doped zinc oxide from 3.11 to 2.9 eV with increasing Al doping. Photoluminescence spectra (PL) exhibited a decrease in peak intensity, suggesting enhanced conductivity in ZnO, also confirmed from I-V measurements. Near-edge X-ray absorption fine structure (NEXAFS) analysis depicts that charge transfer from Al to oxygen (O) species enhanced the photosensing properties of the nanostructure, which was supported by FESEM micrographs and PL spectra. Furthermore, the study discovered that 5% Al co-doping significantly reduced the density of emission defects (deep-level) in Cu–ZnO nanostructure. These findings highlight the potential of Cu and Al co-doped ZnO materials for perovskite solar cell electrodes, as their improved optical and morphological properties resulting from charge transfer could enhance device performance. The investigation of charge transfer and X-ray absorption characteristics provides valuable insights into the underlying mechanisms and behaviors of the co-doped ZnO nanostructures. However, further research is required to delve into the intricate hybridization resulting from charge transfer and explore the broader impact of co-doping on other properties of the nanostructures, enabling a comprehensive understanding of their potential applications in perovskite solar cells.

Effect of Al co-doping on the phase transition of V-doped ZrO<sub>2</sub>

Effect of Al co-doping on the phase transition of V-doped ZrO<sub>2</sub>

Computational study of electronic, magnetic, and optical properties of Fe(II) mono-doped and (Fe(II), Al) co-doped ZnTe

Future information technology will rely mainly on spin-related optical properties; however, these properties require microscopic anti-ferromagnetic coupling, ferromagnetic coupling between d-states, or magnetic interaction between transition metal ions and excitons, all of which are poorly understood in these diluted magnetic semiconductors (DMS). In the present work, we performed first-principles calculations to study the magnetic, opto-electronic properties of Fe(II)-doped ZnTe. The results show that Fe(II) doping at the Zn site changes the ground state of ZnTe from non-magnetic to magnetic, with total magnetization of 4 μB. The observed competing ferro- and anti-ferromagnetism in Fe(II)-doped ZnTe can be described on the basis of the RKKY-exchange process. However, the electron introduced by Al co-doping can change the most stable configuration C-1 from AFM to FM state and an estimated curie temperature above room temperature is obtained. The optical properties of pure ZnTe and doped samples have been calculated, and we find that the bandgap (2.14 eV) of ZnTe is shifted to a lower energy with the increase in Fe(II) doping. The spin-allowed d-d transition of Fe ion in the tetrahedral crystal field is observed in the infra-red region of light. Furthermore, the correlation of magnetic coupling of Fe-ions with optical bandgap energy and d-d intra-band transition bands of Fe(II) has been investigated, and we find that the optical bandgap and spin-allowed d-d transition are blue shifted (red-shifted) in AFM (FM) coupled Fe-ion systems, supporting the experimental observations. The improved opto-electronic and magnetic properties of Fe(II)-doped ZnTe by n-type (Al) co-doping provide insight into the potential applications of these materials in spin-related photonic and spintronic devices such as photovoltaics and remote sensing.

Magnetron Sputtered Al Co-Doped with Zr-Fe2O3 Photoanode with Fortuitous Al2O3 Passivation Layer to Lower the Onset Potential for Photoelectrochemical Solar Water Splitting

In this paper, we investigate the magnetron sputtering deposition of an Al-layer on Zr-doped FeOOH (Zr-FeOOH) samples to fabricate a Zr/Al co-doped Fe2O3 (Al-Zr/HT) photoanode. An Al-layer is deposited onto Zr-FeOOH through magnetron sputtering and the thickness of the Al deposition is regulated by differing the sputtering time. Electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy, Mott-Schottky and time-resolved photoluminescence spectra analyses were used to study, in depth, the correlations between sputtered Al-layer thicknesses and PEC characteristics. High-temperature quenching (800 °C) assists in diffusing the Al3+ in the bulk of the Zr-doped Fe2O3 photoanode, whilst an unintended Al2O3 passivation layer forms on the surface. The optimized Al-Zr/HT photoelectrode achieved 0.945 mA/cm2 at 1.0 VRHE, which is 3-fold higher than that of the bare Zr/HT photoanode. The Al2O3 passivation layer causes a 100 mV cathodic shift in the onset potential. Al co-doping improved the donor density, thus reducing the electron transit time. In addition, the passivation effect of the Al2O3 layer ameliorated the surface charge transfer kinetics. The Al2O3 passivation layer suppressed the surface charge transfer resistance, consequently expediting the hole migration from photoanode to electrolyte. We believe that the thickness-controlled Al-layer sputtering approach could be applicable for various metal oxide photoanodes to lower the onset potential.

Preparation of Al and Sm Co-doped Apatite-Type Lanthanum Silicate Electrolyte and analysis of the conductivity mechanism

The contradiction between the increasing demand for energy and the scarcity of traditional fossil energy sources is becoming increasingly acute, and it is urgent to accelerate the development and use of new, more efficient, and environmentally friendly energy sources. Apatite-type lanthanum silicate solid oxide electrolyte materials (La9.33Si6O26, LSO) are widely used in the field of fuel cell electrolytes due to their high ionic conductivity and high density. In this paper, Al and Sm co-doped LSO solid electrolytes were successfully prepared by the urea-nitrate combustion method. SEM images, relative density, and linear shrinkage of Al and Sm co-doped lanthanum silicate electrolytes sintered at different temperatures were compared. The results show that the best sintering temperature is 1500°C. The electrical conductivity of La9.33SmxSi5.5Al0.5O25.75+1.5x was analyzed by EIS. The conductivity of La9.33Sm0.2Si5.5Al0.5O26.05 is 2.56 × 10−4 S·cm−1 when measured at 600°C. The reason Al and Sm co-doping enhances the conductance is that Al doping generates oxygen vacancies and increases the interstitial oxygen (Oi) concentration. Doping of Sm not only increases the concentration of Oi but also reduces the concentration of cation vacancies, thus improving the conductivity of the electrolyte.

Combined effects of electron doping and surface polarity on the ferromagnetism in Gd implanted polar ZnO wafers

The microstructural, electrical and magnetic properties of Gd-doped and (Al, Gd) codoped Zn-polar and O-polar ZnO wafers manufactured by the ion implantation method are systematically and comparatively investigated. We report an intrinsic ferromagnetic behaviour of Gd-implanted polar ZnO wafers enhanced by Al codoping. It was found that the saturation magnetization for the doped O-polar ZnO wafer is stronger than that of the implanted Zn-polar ZnO wafer. The introduction of Al ions into Gd-implanted polar ZnO enables a further improvement in the ferromagnetism that is directly relevant to the carrier concentration. This finding suggests that the carrier-mediated exchange mechanism may account for the establishment of the long-range ferromagnetic order in the doped ZnO wafers. First-principles calculations confirm that the interaction between the Gd-4 f state and the O-2p state is stronger in oxygen polar ZnO, producing a higher magnetic moment. The increase in the magnetic moment of (Al, Gd) co-implanted ZnO is mainly derived from hybridization of the Al and O orbitals. Our results confirm that larger ferromagnetism can be obtained in Gd-doped O-polar ZnO wafers and that the magnetization can be effectively improved by controlling the electron doping concentration, which highlights the viability of developing spintronic devices based on polar ZnO by codoping magnetic ions and group Ⅲ elements.

Effects of Li/M (M = Al, Ga, In, and Er) co-doping on the electrical properties of BiFeO3–BaTiO3 ceramics

Effects of Li/M (M = Al, Ga, In, and Er) co-doping on the electrical properties of BiFeO3–BaTiO3 ceramics

Effects of Al and Ti co-doping on the strength-ductility- corrosion resistance of CoCrFeNi-AlTi high-entropy alloys

In order to design and develop new marine structural materials with a balance of strength-toughness-corrosion resistance, in this work, the synergistic effects of Al and Ti on the microstructure, mechanical and corrosion resistance properties of CoCrFeNi(Al0.3Ti0.2)x high-entropy alloys were systematically investigated. With the addition of Al and Ti, the L12-γ' phase formed in the alloys significantly improves the mechanical properties, but excessive addition will lead to the formation of Al-Ti-rich B2 phase structure, which reduces the ductility of the alloy. For the corrosion resistance of the alloys in 3.5 wt. % NaCl solution, the increase of Al and Ti contents improves the stability of the passive film, while effectively reduces the corrosion current density and passivation current density of the alloys. However, the precipitation with a large number of strengthening phases aggravates the segregation of elements, resulting in a decrease in the pitting corrosion resistance and the resistance to the pit propagation of the alloy. In addition, compared with conventional structural alloys, the L12-strengthened dual-phase CoCrFeNiAl0.15Ti0.1 high-entropy alloy possesses an excellent balance of strength-toughness-corrosion resistance. This work also provides guidance for the future development of high-performance high-entropy alloy systems for marine engineering.