Lithium Doping Research Articles

Tailoring Li assisted CZTSe film growth under controllable selenium partial pressure and solar cells.

It is still critical to prepare a high-quality absorber layer for high-performance Cu2ZnSnSe4 (CZTSe) multi-component thin film solar cell. The gas pressure during the selenization process is commonly referred to as the pressure of inert gas in the tube furnace, while the exact selenium partial pressure is difficult to be controlled. Therefore, the grain growth under different selenium partial pressures cannot be made clear, and the film quality cannot be controlled as well. In this work, we use a sealed quartz tube as the selenization vessel, which can provide a relatively high and controllable selenium partial pressure during the selenization process. To further tailor the grain growth, lithium doping is also utilized. We find that lithium can greatly promote the growth of CZTSe films as the selenium partial pressure is controlled near the selenium saturation vapor pressure. Combined with ALD-Al2O3, the crystallization quality of CZTSe absorber films is significantly enhanced and the efficiency of CZTSe solar cells achieved a significant improvement. This work clarifies the effect of controllable Se pressure on CZTSe film growth and can lead to better results in CZTSe and other multi-compound thin film solar cells.

Highly sensitive optical thermometer based on Li+-doped erbium ytterbium silicate films

This work provides a new material, Li+-doped erbium ytterbium silicate, with reliable and high temperature sensing sensitivity for optical thermometers. The Li+-doped erbium ytterbium silicate films were prepared by RF magnetron sputtering. The film shows strong green visible emission, which is related to the radiation transitions from thermally coupled energy levels 2H11/2, 4S3/2 to 4I15/2. Lithium doping reduces the field symmetry around erbium and improves the radiation transition efficiency, and Yb doping improves the pump light absorption. Lithium or ytterbium is advantageous to enhance up-conversion luminescence and temperature sensing sensitivity of erbium ions. Therefore, the temperature dependence of green up-conversion luminescence in the range of 80–460 K of the Li+-doped erbium ytterbium silicate films have been found to be a promising optical thermometer material with a high relative sensitivity of 16.9 % K−1, which is higher than the optimum value of other Er3+ materials. In addition, we have provided a preliminary temperature measurement scheme based on the Li+-doped erbium ytterbium silicate film.

Lithium doping's effects on the microstructural, dielectric, energy storage, optical and electrical properties of BaTi0.89Sn0.11O3 ceramics

The present study discusses the synthesis of lithium-doped barium stannate titanate BaTi0.89Sn0.11O3 (BTS11) using sol–gel synthesis route and explores the influence of the lithium content on their structural, morphological, ferroelectric, optical, and electrical properties. The phase of the sol–gel prepared samples with different atomic composition BaLixTi0.89Sn0.11O3(BLxTS11), with x = 0 %, 2 %, 4 %, 6 %, 8 and 10 %, was investigated using X-ray diffraction (XRD) revealing the formation of pure perovskite exhibiting lattice strain. Structural characterization was additionally conducted using Raman spectroscopy to detect structural and the chemical environment modifications caused Li incorporation. The doping induced variation also in the morphology and grain size of BLxTS11 pellets studied using SEM micrographs, which revealed evident grain size changes inversely proportional to the BLxTS11 lattice strain. The samples were then inspected for their ferroelectric properties. The maximum dielectric constant of all samples was observed at a temperature of around 45–50 °C. In addition, correlations between the chemical, structural, and morphological properties of the BLxTS11 ceramics and their energy storage capabilities were established. According to the P-E hysteresis behavior, BL6TS11 ceramic (x = 6 %) ferroelectric demonstrated the highest energy-storage capabilities, with a recoverable energy-storage density of 225 mJ/cm3 and an energy-storage efficiency of 60 %. The optical and electrical properties of the material were also investigated revealing a decrease in the band gap values and a significant increase of resistivity by Li doping.

The impact of lithium concentration on the optical properties of colloidal ZnO nanocrystals

In this work, Li-doped ZnO nanocrystals (LZO) were synthesized via the sol–gel method. The concentration of zinc acetate has been set at 2 M in order to prepare the highly concentrated Li-doped ZnO sol. The generated LZO sol’s optical characteristics were assessed using UV–visible absorption and photoluminescence spectroscopy, while the ZnO nanopowders’ lithium doping process was assessed using XRD and Raman spectroscopy. The experimental findings indicate that the concentration of Li+ ions in the synthesized zinc oxide nanocrystals has reached the maximum solid solubility limit. The inclusion of Li+ ions results in a reduction in the size of ZnO nanocrystals, accompanied by a notable increase in violet-blue emission, distinguishing them from other materials reported in the literature. As can be found, Li+ ions cannot change the type of conductivity in thin ZnO films, and they have n-type conductivity.

Electronic and optical properties of lithium-doped boron nitride nanoribbons using density functional theory

Density functional theory has been utilized to compute the electronic and optical characteristics of zBNNRs (w = 6 and 8) doped with lithium. The results suggest that the simulated nanoribbons display properties similar to those of semiconductors. Furthermore, the graphs demonstrate that a 4% lithium doping level decreases the bandgap. The presence of lithium alters the dielectric function of boron nitride nanoribbons (BNNRs) by acting as a donor atom, thereby introducing additional electronic states within the energy bandgap. Additionally, the dopant enhances the static refractive index, particularly in the z-direction. In the energy range of 0–6 eV, both pristine zBNNRs (w = 6) and zBNNRs (w = 8) satisfy the criteria for the transverse-electric mode. Conversely, beyond 3.87 [for Li-doped zBNNRs (w = 6)] and 3.81 eV [for Li-doped zBNNRs (w = 8)], the lithium-doped nanoribbons support the transverse-magnetic plasmons.

Electrochemical performance of La0.8A0.2TiO3-δ (A = Li, Mg) based perovskites for solid oxide fuel cell electrode

ABSTRACT For potential use as an electrode in SOFCs, the effects of lithium and magnesium doping for phase development and conductivity of LaTiO3 have been investigated. Using a 1000°C sintering temperature, dense ceramics are created via the traditional solid oxide reaction method. Phase study shows the presence of perovskite phase with monoclinic crystal assembly. Structural characteristics of doped and undoped perovskites were calculated using the VESTA tool. Through the computed XRD spectral analysis, unit cell dimensions are established. To quantify sub-atomic characteristics and examine lattice components, CrystalMaker software also calculates electron density and lattice range. CrystalMaker program is useful for simulating porosity distributions and analysing impure inclusions in crystallisation.The electrical conductivity of the perovskites was analysed using impedance spectrometry and Li-doped structures display a significant increase in conductivity in the phase borderline of disordered perovskite.

Preparation and electrochemical properties of a ceramic solid electrolyte with high ionic conductivity, Li1.3Al0.3Ti1.7(PO4)3

The emergence of lithium-ion solid electrolytes greatly increases the safety risk of liquid electrolytes. Among the many solid electrolytes, aluminum-doped Li1.3Al0.3Ti1.7(PO4)3(LATP) has become a research hotspot due to its high ionic conductivity and good air stability. However, the traditional high-temperature sintering process has the problems of lithium volatilization and secondary phase formation. Therefore, it is very difficult to prepare high-quality LATP solid electrolytes. The X-ray diffraction pattern and analysis showed that the LATP samples prepared in this paper showed rhombohedral structure and could be indexed by the R3c space group, and a new method of excess lithium compensation sintering was proposed, in which lithium compensation (LiNO3) could well reduce the impact of lithium volatilization. It can be used as a sintering additive to promote the sintering densification of LATP. In this paper, the optimal sample for sintering at 900°C was determined by measuring the microstructure and electrochemical properties of the electrolyte, and lithium doping was studied. The LATP solid electrolyte with 10 wt% lithium doped has a conductivity of 7.2× 10−4 S/cm and a low activation energy (0.278 eV). Its mechanical properties (elastic modulus and hardness) are the best, which are 103.024 GPa and 8.053 GPa, respectively, and the value of its elastic modulus is much greater than that of lithium metal shear modulus of 4.25 GPa, which can effectively inhibit the growth of lithium dendrites. And the magnitude of the grain boundary conductivity and particle size of the lithium-doped sample correspond to the dielectric constant results.

Synthesis and Characterization of Lithium-doped BaTiO3/Si(100) Thin Films with Variations of 0 %, 0.5 %, 1 % and 1.5 % as Potential Forerunners of Solar Cells

Thin films of BaTiO3/Si(100) in Lithium with doping variations of 0%, 0.5%, 1%, and 1.5% were successfully grown on a p-type Si substrate using Chemical Solution Deposition method. The films were annealed at 850 °C for 15 hours. The crystal structure was characterized using X-Ray Diffraction (XRD) with Material Analysis Using Diffraction (MAUD), Scanning Electron Microscope- Energy Dispersive X-Ray (SEM-EDX), optical absorption, and current – voltage (I-V) as potential solar cells. The results showed that the addition of Lithium doping affected the value of the lattice parameters and formed tetragonal crystals. The characterization results show that the bandgap energy value of the thin film due to lithium doping reduces the bandgap energy value because the donor atom added to a semiconductor causes the allowable energy level to be slightly below the conduction band. The presence of this new band causes the thin film bandgap energy to decrease with a five-valent tantalum dip. The morphological properties showed that the BaTiO3/Si(100) thin film particles in the deposited Lithium had a reasonably homogeneous grain. With the addition of lithium acetate as a binder into barium titanate, the grain size is getting smaller because it is suspected that the lithium-ion radius is smaller than the barium-ion radius. Measurement of I-V on the thin film shows that the output voltage value increases with more light intensity hitting the surface of the thin film. The greater the light intensity, the greater the energy of the photons, so the electrons are easier to jump. The three things above (both electrical and morphological properties) conclude that the thin films grown have the potential for solar cells.

Effect of tensile deformation on the optoelectronic properties of black phosphine-doped lithium atoms.

First-principles calculations based on the generalized gradient approximation gradient and the Perdew-Burke-Ernzerhof function (GGA-PBE generalized function) are carried out on the intrinsic and lithium-doped black phosphine systems to investigate the effects of different uniaxial tensile deformations on the electronic and optical properties of the systems. It is shown that the structural stability of the intrinsic and lithium-doped systems decreases with increasing tensile deformation, and all systems are most stable at 0% tensile deformation. The intrinsic black phosphazene system is a direct band gap semiconductor, and its band gap increases and then decreases with tensile deformation and reaches a maximum value of 1.086eV at 4%. Lithium doping closes the band gap of the black phosphazene system, which is metallic in nature, but the band gap is opened up when the tensile deformation is 4-6%. From the density of states analysis, the density of states of all systems is basically contributed by the s and p orbitals, with little contribution from the d orbitals, and the contribution from the p orbitals is dominant. From the analysis of optical properties, the increase of tensile deformation causes the absorption peaks of the intrinsic system to redshift then blueshift then redshift, causes the absorption peaks of the lithium-doped system to redshift, and causes the reflection peaks of all systems to redshift. In addition, lithium doping blueshifts the absorption and reflection peaks of the systems compared to the intrinsic black phosphazene system. Using the CASTEP section of the Materials Studio software, first-principle calculations based on density functional theory are done on the top-site doped lithium atoms of monolayer black phosphine under uniaxial stretching deformation in the a-direction, and the generalized gradient approximation gradients and Perdew-Burke-Ernzerhof functions (GGA-PBE generalized functionals) are used for the optimization and approximation process. The optimization parameters are set for the supercell structure: its plane-wave truncation energy is set to 400eV, its Brillouin zone K-point grid is set to 3*3*3, its self-consistent field iteration accuracy convergence value is 2.0e-6eV/atom, the convergence basis of its structural optimization is 0.02eV/ Å, and the convergence of the stress value is 0.05 gpa. During the optimization period, the interaction force between atoms is 0.03eV/ Å and the atomic displacement is less than 0.001Å. To eliminate the effect of interlayer forces, a vacuum layer with a thickness of 15Å is placed in its vertical direction (i.e., c-axis direction).

Lithium doping in Na-based double perovskite for hydrogen storage and improving their optoelectrronic properties: First-principles investigation

The effect of lithium doping on novel double perovskite materials for hydrogen storage has been investigated through first-principles calculation. The lithium doping would cause phase change due to different crystal symmetry. Based on tolerance factors, cohesive energy and Born-Huang criteria, the materials are all stable. The analysis of hydrogen storage properties indicates that lithium doping can both improve the gravimetric storage capacity to 4.41% and 5.08%, and decrease the desorption temperature to 348.7 K and 325.0 K for K2LiScH6 and K2LiAlH6, respectively. And to a certain extent, the introduction of lithium improves the optoelectronic properties especially the photoresponse in ultraviolet region, which demonstrates the applicable potential in photocatalysis. The results are consistent with the wide bandgap values. Our study provides some reference for further experimental studies of double perovskites in hydrogen storage materials.

Modulating the Electrical Properties of Lithium-Doped Zinc Oxide: Interplay of Lithium Content, Oxygen Pressure, and Temperature

This research elucidates the intricate interplay of lithium content, oxygen pressure, and temperature and their influence on the electrical properties of Lithium-doped zinc oxide (LZO). The electrical behavior of zinc oxide (ZnO), a prominent semiconductor material, can be modulated when doped with lithium (Li). Through systematic experimentation, we demonstrate that varying lithium content in the ZnO matrix leads to notable shifts in carrier concentration and mobility, which in turn impacts the material's conductivity and overall electrical performance. Furthermore, oxygen pressure during synthesis plays a pivotal role in defect formation, especially oxygen vacancies, which interact dynamically with lithium dopants to further modulate electrical behavior. Introducing the variable of temperature, our study reveals a synergistic effect, where temperature not only affects intrinsic carrier concentration but also the interactions between lithium dopants and inherent defects in ZnO. Under optimized conditions of oxygen pressure and temperature, the influence of Li content on crystallinity was pronounced, consequently impacting mobility. In contrast, under unoptimized conditions, as Li concentration increased, particularly beyond optimal levels (0.75 mol%), introduced Li atoms assumed the role of compensating centers by capturing or neutralizing carriers, reducing mobility. The findings presented herein provide a comprehensive understanding of how these factors collectively determine the electrical properties of LZO, paving the way for tailored applications in optoelectronic devices, sensors, and more.

Lithium doping enhanced ORR kinetics and CO2 tolerance of iron-based double perovskite cathode for solid oxide fuel cells

Fe-based double perovskites exhibit significant potential as cathode materials for solid oxide fuel cells (SOFCs) owing to their affordability, moderate thermal expansion, and impressive stability. Nevertheless, their practical utility has been constrained by their comparatively lower oxygen reduction reaction (ORR) catalytic activity. In this study, for the first time, lithium (Li) was employed as a dopant to improve the ORR activity of the Fe-based double perovskite PrBaFe2O5+δ (PBFO). The results indicated that the ratios of Fe3+/Fe2+ and Oads/Olat were effectively tuned by incorporating Li at Ba-sites of PBFO. Consequently, the adsorption and dissociation of oxygen, along with the charge transfer processes were regulated significantly, resulting in an increase in ORR kinetics and improved CO2 resistance. At 800 °C, PrBa0.9Li0.1Fe2O5+δ (PBLFO) demonstrated an Rp of 0.072 Ω cm², which was decreased by 43.3% compared to PBFO. Simultaneously, the maximum power density of PBLFO-based full cell was improved by 23.3%, reaching 670 mW cm−2. These findings suggest that Li-doping holds great potential for improving the performance of Fe-based SOFC cathodes, thereby contributing to the advancement of clean and sustainable energy technologies.

Structural Evolution of Lithium-Exchanged Na3(VO)2(PO4)2F Cathode under Operation in Sodium Ion Batteries.

Na superionic conductor (NASICON)-type Na3(VO)2(PO4)2F (NVOPF) exhibits excellent cycling stability for high-voltage sodium ion batteries. Various strategies have been developed to form ion-exchanged NVOPF which can enhance the ionic and electronic conductivity. However, the underlying ion transport mechanism and complex structural transitions during battery operation remained uninvestigated. In this work, we prepared lithium-exchanged NVOPF (namely NLVOPF) which shows improved ionic conductivity and increased capacity at high discharging rates. Solid-state nuclear magnetic resonance (SSNMR) revealed the distinctive presence of two kinds of Li-exchanged sites in the NLVOPF, which are attributed to the occupied lithium ions at the Na1 and Na2 sites (namely Li1 and Li2, respectively). The Li1 site was metastably replaced in the first cycle, yet the Li2 site participated in ion insertion/extraction in the subsequent cycles. Our characterizations show that the dynamic doping of lithium in NLVOPF could contribute to the improved cycling stability and capacity retention.

Effect of lithium doping on frequency-dependent dielectric properties of manganese ferrite nanoparticles

Effect of lithium doping on frequency-dependent dielectric properties of manganese ferrite nanoparticles

Improving photoluminescence properties and reducing recombination of CsPbBr3 perovskite through lithium doping.

This study investigates the impact of lithium doping on the structural and photophysical properties of spin-coated CsPbBr3 perovskite thin films. The deposited films display a pristine structure, preferentially growing along the (220) direction, and exhibit high-quality green photoluminescence at around 530 nm. The doping leads to an improvement in the optical properties of the films, as evidenced by a stronger photoluminescence (PL) intensity compared to undoped CsPbBr3, particularly at temperatures below 200 K. The increase in PL intensity suggests a decrease in defects and surface passivation. Additionally, the decrease in the power-law exponent β from 1.6 to 1.0 indicates a reduction in non-radiative recombination, likely due to trap states filling with free electrons induced by the doping. Overall, doping with lithium reduces non-radiative recombination, fills trap states, and reduces band tail/activation energy, leading to improved optoelectronic properties of the films. This investigation provides insights into the photophysical properties of the Li-CsPbBr3 absorber layer and the recombination mechanism, and helps to unravel new methods for the development of high-stability, high-performance perovskite thin-film solar cells and optoelectronic devices.

Sol–Gel Synthesis of ZnO:Li Thin Films: Impact of Annealing on Structural and Optical Properties

A sol–gel deposition approach was applied for obtaining nanostructured Li-doped ZnO thin films. ZnO:Li films were successfully spin-coated on quartz and silicon substrates. The evolution of their structural, vibrational, and optical properties with annealing temperature (300–600 °C) was studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-VIS spectroscopic, and field emission scanning electron microscopic (FESEM) characterization techniques. It was found that lithium doping maintains the wurtzite arrangement of ZnO, with increasing crystallite sizes when increasing the annealing temperature. Analysis of the FTIR spectra revealed a broad main absorption band (around 404 cm−1) for Li-doped films, implying the inclusion of Li into the ZnO lattice. The ZnO:Li films were transparent, with slightly decreased transmittance after the use of higher annealing temperatures. The porous network of undoped ZnO films was transformed to a denser, grained, packed structure, induced by lithium doping.

Achieving Cross-Ring Fragmentation of N-Linked Glycans by IR-MALDESI.

Glycans are complex structures that require MS/MS for detailed structural elucidation. Incorporating metals can provide more structural information by inhibiting glycosidic cleavage and enhancing cross-ring fragmentation. A direct analysis was performed using lithium doping and IR-MALDESI to induce cross-ring fragmentation of glycans. The protonated and lithiated versions of the two glycans were isolated and subjected to HCD. For protonated glycans, only glycosidic cleavages were observed. Using lithium doping, MS/MS consisted of abundant cross-ring fragments. Seventeen cross-ring fragments were detected across both glycans using lithium-doped ESI. This is the first incorporation of metal doping in IR-MALDESI to achieve cross-ring fragments in MS/MS analysis.

Synthesis and characterization of lithium-doped copper zinc tin sulfide (CZTS) thin films

The non-toxic nature and remarkable optoelectronic properties of kesterite (Cu2ZnSnS4 and CZTS) make CZTS a potential candidate for solar cell absorber layer material. Since alkali metal doping has shown a performance boost of active layers of solar cells, this work investigates the effects of significant lithium doping on sol-gel-produced CZTS thin films. CZTS- and lithium (Li)-doped CZTS thin films were prepared using the spin coating technique. The variation of structural, morphological, and optical properties of CZTS due to Li-doping has been studied by x-ray diffraction, scanning electron microscopy, and UV–visible spectroscopy techniques. All the synthesized LixCu2−xZnSnS4 (x = 0, 0.2, 0.4, 0.6) films showed fine crystallinity with average crystallite sizes of 4.745, 6.013, 6.255, and 6.404 nm, respectively. The average grain size decreases from 0.336 to 0.310 µm via increasing Li concentration. The inclusion of Li increased the bandgap energy ranges from 1.5 to 1.808 eV. The Li0.6Cu1.4ZnSnS4 thin showed the highest absorption coefficient of 3.505 × 104 cm−1 among all the prepared thin films. A high optical conductivity over 1014 s−1 was observed for CZTS, which further increased with an increased Li concentration. The synthesized structures showed enhanced characteristics suitable for solar cell application.

Comparison between Lithium Substitution and Doping on the Physical and Piezoelectric Properties of Lead-Free BCZT Ceramics

Defects generation in ceramics by element substitution or doping may improve their properties. However, different results will be obtained even though the same element is involved due to different mechanisms. Ceramics Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) is one of the potential candidates to replace lead-based material PZT. However, the conventional method requires high-temperature calcination and sintering process to synthesize this material. Thus, Lithium (Li) can act as the sintering aid to lower the temperature at the same time, the properties of piezoelectric can be enhanced. In this paper, the structural, physical, and piezoelectric performance of lead-free Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) ceramics with Lithium Li substitution and doping, synthesized by the solid-state reaction method were studied. The substitution of Li increases the density, ρ and piezoelectric coefficient, d33 of BCZT which are 4.075 g/cm3 and 304.6 pC/N, respectively. These results demonstrate that Li substitution is more beneficial to the piezoelectric properties than doping because it produces higher grain boundary resistance and activation energy and has lower conductivity than doping. This can provide a definite strategy during the chemical composition design and manufacture of BCZT ceramics.

The Synergetic Ionic and Electronic Features of MAPbI3 Perovskite Films Revealed by Electrochemical Impedance Spectroscopy

AbstractPerovskites have emerged as a forerunner of electronics research due to their vast potential for optoelectronic applications. The numerous combinations of constituent ions and the potential for doping of perovskites lead to a high demand to track the underlying electronic properties. Solution‐based electrochemistry is particularly promising for detailed and facile assessment of perovskites. Here, electrochemical impedance spectroscopy (EIS) of methylammonium lead iodide (MAPbI3) thin films is performed and model them with an equivalent circuit that accounts for solvent, ionic, and thin film effects. A dielectric constant consistent with prior AC studies and a diffusion constant harmonious with cation motion in MAPbI3 are extracted. An electrical double layer thickness in the perovskite film of 54 nm is obtained, consistent with lithium doping in perovskite films. Comparing the EIS and equivalent circuit model of perovskite films to control ITO‐only data enabled the assignment of the ions at each interface. This comparison implied a double layer of primarily lithium ions inside the perovskite film at the solution interface with significant recombination of ions on the solution side of the interface. This demonstrates EIS as a powerful tool for studying the fundamental charge accumulation and transport processes in perovskite thin films.