Optoelectronic Applications Research Articles

Ultralow Thermal Conductivity and Very High Seebeck Coefficient in Two-Dimensional TeSe2 Semiconductor.

Emerging chalcogenide-based two-dimensional (2D) materials possess various unique yet fully explored properties and are thus considered promising candidates for next-generation optoelectronic and energy conversion applications. Here, TeSe2 crystals with interesting thermoelectric features were synthesized using a simple solid-state reaction. High-resolution transmission electron microscopy reveals that TeSe2 stabilizes in a 2D atomic structure with helical chains, resembling 2D tellurene. The thermoelectric properties were measured from 2 to 390 K in a polycrystalline pellet, showing an ultralow thermal conductivity below 0.25 W m-1 K-1 and a very high positive Seebeck coefficient of up to 865 μV K-1. Particularly, the thermal conductivity shows a hysteresis effect upon temperature cycling, which is tentatively explained as cracks opening and partially closing. Optical measurements indicate that TeSe2 is a semiconductor with two bandgaps at 1.43 and 1.65 eV. These results highlight that TeSe2 is an intriguing 2D semiconductor with complex thermoelectric properties, which provides a platform to further study the interplay of emerging 2D structure, thermal, and electronic properties.

Ab-initio atomistic insights into lead-free perovskites for Photovoltaics Technology

The primary objective of this manuscript is to enhance knowledge and comprehension of hexagonal perovskites KNiX3 (X=I, Br). The world is fascinated by halide perovskites because of their advancements in opto-electronic applications, particularly in the photovoltaic field. KNiI3 and KNiBr3 halide perovskites correspond to the two anion I and Br. Here we aim to investigate how opto-electronic applications are affected by the substitution of cations and anion. Within the framework of density functional theory (DFT), the structural, electronic, and optical properties have been computed using the PBE GGA approximation. Br-based perovskites have a shorter bond length than I-based compounds because iodine ions have a larger ionic radius than bromine ions. Thus, the lattice constant increases from I-based potassium halide perovskites to Br-based potassium halide perovskites. The values of the lattice constant match the results of experimental computations. The Density of States (DOS) curves and band structure are used to examine the contribution of the bands. From Br to I, there is a reduction in the band gap, indicating an improvement in photovoltaic applications. Various energy ranges are used to calculate the optical spectra, dielectric function, absorption coefficient, optical reflectivity, and refractive index. KNiX3 (X=I, Br) compound reveals low reflection value which is typically an excellent choice for photovoltaic and opto-electronic applications.

The influence of bandgap tunability on the physical features of Rb2LiSbX6 (X=Cl, Br) double perovskites in the context of green technologies

Rubidium-based perovskites have the potential to significantly transform renewable energies by making devices more affordable and environmentally friendly. The DFT is employed to conduct an inclusive analysis of the elastic, structural, electronic structure, transport and optoelectronic properties of Rb2LiSbCl6 and Rb2LiSbBr6. The analysis of tolerance factor, optimization curves and octahedral tilting serves to validate the structural stability. The brittle character of Rb2LiSbCl6 and ductile nature of Rb2LiSbBr6 are substantiated by their mechanical properties. The (W-L) symmetry points for Rb2LiSbCl6 and Rb2LiSbBr6 demonstrate the indirect bandgap of 3.72 eV and 2.9 eV, respectively. A decline in the bandgap is observed upon substitution of the Cl with Br atom. The Kramer-Kronig relations are employed for the assessment of the optical properties, revealing substantial absorption within the UV spectrum for both structures, hence enabling their application in optoelectronics. A wide range of thermoelectric properties are computed utilizing the Boltzmann semi-classical theory. Perovskites possess considerable promise for the implementation of renewable energy applications due to their notable ZT values (i.e., 0.73 for Rb2LiSbCl6 and 0.74 for Rb2LiSbBr6), as well as their enhanced Seebeck coefficients. These characteristics enhance their appropriateness for usage in green technologies.

Electronic, thermodynamic, NLO, and spectroscopic properties of OAFLC compounds via DFT: A focus on 1F6B, 1F6Bi, 1F6BiN, and 1F6BN

This study presents a comprehensive quantum mechanical investigation of four novel liquid crystalline compounds: 1F6B, 1F6Bi, 1F6BiN, and 1F6BN. Using Density Functional Theory (DFT) with the B3LYP functional and 6-311G(d,p) basis set, we optimized the molecular geometries and analyzed their electronic and vibrational properties. Atomic Polar Tensor (APT) charge analysis showed significant charge distributions. Electrostatic potential (ESP) mapping identified potential reactive sites, while Electron Localization Function (ELF) and Localized Orbital Locator (LOL) analyses depicted the electron density distributions. Thermodynamic parameters indicated the compounds’ vibrational stability and responsiveness to thermal changes. Non-linear optical (NLO) properties were characterized by significant dipole moments and polarizabilities, suggesting potential in optoelectronic applications. Frontier molecular orbital analysis indicated stability with HOMO-LUMO gaps ranging from 4.15 to 4.64 eV. UV–Vis spectra revealed key electronic transitions, while Raman spectroscopy detailed various vibrational modes. The study offers valuable insights into the molecular behavior of these compounds, laying the groundwork for their future applications in material science and advanced technologies.

Thermally stable white light emission and energy transfer analysis of tungstate-tellurite glasses co-activated with Dy3+/Eu3+ for optoelectronic applications

In this study, dual ions (Dy3+/Eu3+) doped tungstate-tellurite (TWKZBi: Dy3+/Eu3+) glass matrices have been formed with the help of the melt quenching approach. The structural, thermal, morphological, and photoluminescent (PL) characteristics, as well as the energy transfer (ET) processes were thoroughly investigated. The structural features of the titled glasses have been explored via X-ray diffraction (XRD) analysis. The morphology and elemental studies of the titled glass matrices were verified with the help of field emission scanning electron microscopy (FE-SEM) along with energy dispersive spectroscopy (EDS). The PL results designate that the TWKZBi doped with Dy3+ ions glass samples exhibit a strong emission peak at 575 nm when excited via n-UV light, whereas Eu3+ doped TWKZBi glass sample demonstrates a conspicuous red emission band at 614 nm when stimulated with the n-UV light. In addition, TWKZBi glasses doped with both Dy3+ and Eu3+ ions demonstrate the emission peaks in the blue (B), yellow (Y) and red (R) zones of the electromagnetic spectrum. The combination of these peaks generates white and orange-red light through properly controlling the activator ion concentrations and selected excitations. Based on Dexter's and Reisfeld's approximation, dipole-dipole (d-d) interaction is responsible for the transfer of energy from donor (Dy3+) to accepter (Eu3+) ions. The decay profiles demonstrate the bi-exponential behavior with a decline in the average lifetime (τavg) values as varying activator (Eu3+) ion concentrations in the titled TWKZBi: Dy3+/Eu3+ glasses. All the results above validate that the titled TWKZBi: Dy3+/Eu3+ glass samples could be fascinating for white LEDs and other optoelectronic applications.

Investigation on growth, structural, spectral, optical, thermal, third order nonlinear optical and DFT studies of dibenzoylmethane single crystal for photonic and optoelectronic applications

Investigation on growth, structural, spectral, optical, thermal, third order nonlinear optical and DFT studies of dibenzoylmethane single crystal for photonic and optoelectronic applications

Green synthesis of 2-trifluoromethylquinoline skeletons via organocatalytic N-[(α-trifluoromethyl)vinyl]isatins C-N bond activation

The Pfitzinger reaction has long served as a notable synthesis pathway for quinoline-4-carboxylic acids. Although recognized for its synthetic potential since its discovery more than 138 years ago, a truly catalytic variant has remained elusive until now. Herein, we present a novel 2-tert-butyl-1,1,3,3-tetramethylguanidine (BTMG)-catalyzed Pfitzinger reaction that employs N-[(α-trifluoromethyl)vinyl]isatins with amines and alcohols, providing direct routes to 2-CF3-quinoline-4-carboxamides and carboxylic esters. This method is not only green and environmentally benign but also accommodates the introduction of other functional groups like CF2H and CO2Me at the C2 position of quinoline skeleton. The utility of this methodology was demonstrated by the broad substrate scope, the late-stage modification of commercial drugs, and the diverse derivatization of quinoline framework. More importantly, this work not only opens up a new avenue for the activation of amide C-N bonds in catalytic reaction development, but also unlocks the huge potential of some 2-trifluoromethyl quinolines with strong inhibitory activity against PTP1B or optoelectronic application in organic light-emitting diodes.

Investigations of optoelectronic and scintillating properties of novel halide perovskites Cs2KSnX6 (X=Cl, Br, I)

In this paper, using density functional theory (DFT) formalism, optoelectronic properties of new halide perovskites Cs2KSnX6 (X=Cl, Br, I) are explored. The lattice constants of these double perovskites with and were found to be and respectively. Trans-Blaha modified Becke-Johnson (TB-mBJ) exchange-correlation functional was used to calculate the energy bandgap by incorporating spin-orbital coupling effects into it. The double perovskite with was observed to possess a higher band gap value due to the increase in the size of halide anions. Due to the inverse relationship between bandgap values and lattice constants, it has been observed that increasing the lattice constant results in the decrease of the electronic band gap and vice versa. From the density of states calculations, the nature of the electronic states involved in forming the energy bands has been determined. The upper light yield (LY) with the limit of 100% under ideal conditions is found to be 544217 ph/MeV, 950118 ph/MeV, and 1600000 ph/MeV for , and respectively, which suggests their potential applications in scintillating devices. Moreover, the optical properties like complex dielectric functions, absorption coefficients, reflectivity, and refractive index are calculated for these new proposed compounds. A systematic analysis of the optical and scintillating properties suggests the usefulness of among other compounds, as a potential candidate for high-energy radiation detection and other optoelectronic applications.

Quantum yield, energy transfer, and x-ray induced study of Sm3+ ions doped oxide glasses for intense orange-red photo-emitting optoelectronic device applications

The work elucidates detailed analysis of X-ray near edge structure of Gd3+ ions using Synchrotron studies and deciphers the energy transfer mechanism involved in the stoichiometric ratio of (79-x)B2O3 + 10ZnO + 10BaO + xGd2O3 + 1Sm2O3 (BZBGS; x = 0, 5, 10, 15, 20 mol.%) glasses. A detailed analysis of the glasses’ optical, structural, and luminescence properties were instigated to understand light emitting behaviour. The oxidation state of Gd atom inside the glass found to be + 3. Stimulated emission cross section, radiative transition probability and branching of the metastable state of rare-earth ions were evaluated using Judd-Ofelt model and compared with other reported literature. Photo-Emission spectra were monitored at the UV-C band and X-rays. Luminescence was analysed with various excitation wavelengths and sources. Photoluminescence quantum yield show more than 22 % efficiency and show more than 15 % compared with other reported glasses. Luminescence intensity ratio was analysed and found that the Sm3+-ions do not occupy the inversion-symmetry which enhances the luminescence intensity in the present glass system. The CIE and CCT values were evaluated and discussed.

Investigation of Structural, Electronic, Optical, and Photocatalytic Properties of new double perovskites Cs2InSbX6 (X = F, Cl) under Strain Effects

Inorganic halide perovskites, such as Cs₂InSbX₆ (X = F, Cl), have shown potential for next-generation solar cells and photocatalysis due to their light-capturing properties. However, concerns about stability and toxicity in lead-based perovskites drive the need for eco-friendly alternatives like antimony-based compounds. This study employed Density Functional Theory (DFT) calculations to explore how mechanical strain affects the electronic and optical properties of Cs₂InSbX₆. Without strain, Cs₂InSbF₆ and Cs₂InSbCl₆ exhibit bandgaps of 2.06 eV and 1.20 eV, respectively. We investigated how strain ranging from -5% to +5% influences these materials' performance in optoelectronic and photocatalytic applications. Notably, negative strain enhances absorption and quantum efficiency for both compounds, particularly Cs₂InSbCl₆, which shows superior absorption in the visible spectrum. Our findings suggest that Cs₂InSbCl₆, with a tunable bandgap and favorable optical characteristics under strain, is a promising candidate for environmentally friendly applications, including solar cells and photocatalysis.

Evaluation of Luminescent and Thermal Properties of Dy³⁺ Doped Tungstate Phosphors for Optoelectronic and Thermometry Applications

Novel Ca2MgWO6: xDy3+ (x = 1, 2, 3, 4, and 6 mol%) phosphors were synthesized via solid-state reaction method. The phosphor structure remained unchanged upon doping with Dy3+ ions. Phosphors were optical optimizated using 4F9/2 → 6H13/2 transition, and 3 mol% of Dy3+ was found to be optimal concentration. We investigated optical quenching mechanisms including energy transfer, cross-relaxation, charge compensation, and multipole-multipole interactions. Colorimetric analyses assessed colour coordinates, purity, and correlated colour temperature (CCT). The optimized phosphor showed a direct band gap of 3.68 eV, a refractive index of 2.24, and covalent bonding between Dy3+ and the host. It exhibited exceptional thermal stability with only 0.31 wt% loss up to 440°C. Temperature-dependent emission spectra indicated high optical quenching temperature (498.82 K) and activation energy (0.21 eV). A multi-transition ratiometric approach confirmed suitability for non-contact thermometry and LED applications.

Principles-based investigation of lithium-based halide perovskite X2LiAlH6 (X=K, Mn) for hydrogen storage, optoelectronic, and radiation shielding applications

Scientists devote their time and energy to studying and developing hydrogen storage devices to address the energy crisis and climate change. Because of this, investigations are conducted to reveal the optoelectronic, structural, bader charge, electronic charge density, and hydrogen storage properties of X2LiAlH6 (X = K, Mn) within the framework of density functional theory, and calculations of the structural characteristics were carried out utilizing local and nonlocal, and hybrid functionals. An additional onsite Coulomb parameter (GGA + U), which includes the Hubbard parameter, was used to apply the potential. Calculations based on the Kramer-Kroning principle were used to determine the dielectric function, refractive index, extinction coefficient, and energy loss function. The results indicate that K2LiAlH6 and Mn2LiAlH6 are highly suitable for hydrogen storage applications. The gravimetric ratios of hydrogen storage capacities for both investigated materials are 5.2 wt %, and 7.5 wt %, respectively. The interaction of the Mn-d, Li-s, K-s, and H-s/p orbitals was the cause of hybridization, according to the optoelectronic characteristics. Compound stability is indicated by the negative computed formation energy of the materials under investigation. The electronic charge density analysis showed a mixed-bond semiconductor with low ionicity and high covalence. In addition, the radiation shielding properties of Mn2LiAlH6 and K2LiAlH6 were investigated using Phy-X software, showing promising results in linear attenuation, half-value layer, and mean free path, particularly for Mn2LiAlH6 due to its higher atomic number. This groundbreaking study represents a pioneering computational exploration of X2LiAlH6, offering promising advancements for future research in hydrogen storage applications.

Visible-light-operative photocatalyst based on Er-TiO2 Nanostructures Blended with Room temperature ferromagnetism, band-gap Increment, and high optical transparency

TiO2 thin films doped with Er+3 percentage (1-5wt.%) have been prepared using the sol-gel dip coating technique. Er influences the morphological, structural, magnetic, electrochemical, UV, dielectric, Photoluminescence, and photocatalytic properties of TiO2. FTIR was utilized to examine the different functional groups. The confirmation of the anatase phase formation was established through XRD spectra and FTIR spectra. When the concentration of dopant increased, the crystallite size was found to be decreased from 7.96 to 5.62 nm. A blue shift was noticed in transmission spectra as the dopant concentration increased leading to an increase in the bandgap of thin films. The dielectric properties of all thin films exhibited typical behavior. The barrier height, density of localized states at fermi levels, and hopping distance were examined using AC conductivity measurements. As dopant concentrations increased the dielectric constant increased while AC conductivity decreased. The outcomes of electrochemical charge-discharge tests provided the specific capacitance, power density, and Energy of Er-doped TiO2. Er-doped TiO2 especially at 5wt.% showed significant photocatalytic activity in decomposing indigo carmine under sunlight, suggesting its potential for water treatment, and mitigating environmental pollution. Furthermore, Er-doped TiO2 demonstrated efficient functionality as a CO gas sensor. Er-doped TiO2 exhibited violet photoluminescence, with emission intensity modulated by elevating the Er percentage attributed to heightened defect concentration. These properties find a utility in Optoelectronic device applications. Magnetic analysis indicated that incorporating a trivalent dopant (Er+3) into the Ti-O lattice enhanced ferromagnetic properties.

Si/AlN p-n heterojunction interfaced with ultrathin SiO2

Ultra-wide bandgap (UWBG) materials offer significant potential for high-power RF electronics and deep ultraviolet photonics. Among these, AlxGa1−xN stands out due to its tunable bandgap (3.4 eV to 6.2 eV) and excellent material properties. However, achieving efficient p-type doping in high aluminum composition AlGaN remains a challenge. This study presents a novel approach by fabricating a p+Si/n-AlN/n+AlGaN heterojunction using semiconductor grafting. Atomic force microscopy (AFM) revealed smooth surfaces for AlN and the nanomembrane, with roughness values of 1.96 nm and 0.545 nm, respectively. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirmed a sharp and well-defined Si/AlN interface with minimal defects and strong chemical bonding. X-ray photoelectron spectroscopy (XPS) measurements identified a type-I heterojunction with a valence band offset (ΔEv) of 2.73–2.84 eV and a conduction band offset (ΔEc) of 2.22–2.11 eV. The pn diode devices exhibited linear current–voltage (I-V) characteristics, an ideality factor of 1.92, and a high rectification ratio of 3.3 × 104, with a turn-on voltage of 3.9 V. Temperature-dependent I-V measurements showed stable operation up to 90 °C. The heterojunction’s high-quality interface and impressive electrical performance underscore its potential for advanced AlGaN-based optoelectronic and electronic applications.

First principle study of structural and optoelectronic properties of ZnLiX3 (X = Cl or F) perovskites

The zinc-based perovskites ZnLiX3 (X = Cl or F) were investigated for their structural, electronic, and optical properties using the WIEN2k package within density functional theory (DFT). Structural properties were calculated using the generalized gradient approximation (GGA), while the modified Becke-Johnson (mBJ) potential was applied for a more accurate description of the optical and electronic properties. Both compounds are confirmed to be stable, crystallizing in the cubic Pm-3 m (No. 221) space group. ZnLiCl3 has an indirect band gap of 0.30 eV between the Γ and M symmetry points, indicating semiconducting behaviour, while ZnLiF3 exhibits an indirect band gap of 5.45 eV, typical of an insulating material. The electronic states contributing to the band structure were analyzed using the total density of states (TDOS) and partial density of states (PDOS). Optical properties, evaluated in the energy range of 0–14 eV, reveal strong optical conductivity and absorption at higher energies, while both materials show transparency to lower-energy photons. These findings suggest that ZnLiCl3 and ZnLiF3 are suitable candidates for high-frequency UV optoelectronic device applications.

Femtosecond laser-induced ultrafast electron dynamics and band gap renormalization in InSb

Studying ultrafast dynamical processes is essential for understanding light-matter coupling, which is crucial for the optoelectronic and photonic applications of semiconductor materials. Herein, we investigate the evolution of electron population near the conduction band minimum (CBM) and band gap in InSb (100) crystal under different laser fluences using time- and angle-resolved photoelectron spectra (TrARPES). In contrast to the pump-fluence-independent fast growth process (FP) of the electron population, the slow process (SP) is fluence sensitive, which is similar to the temperature-dependent behavior observed in InSb (110). In addition, we observe a band gap enlargement with increasing the photoexcitation flux. Comprehensive analysis reveals that these observed diverse results are attributed to the laser-tunable dielectric function on the surface of InSb. Our findings not only enhance the understanding of laser-semiconductor interactions but also broaden the potential applications in the field of optoelectronic and photonic devices.

Correlation between structural modifications and physical parameters of Sb doped InSe alloys for optoelectronic applications

Bulk samples of In0.1Se0.9-xSbx (0 ≤ x ≤ 0.24) were synthesized using the conventional melt-quenching technique. The impact of Sb doping on the structural and physical properties of InSe alloys was systematically explored. The substitution of Sb at the expense of Se introduces defects and dislocations in the lattice, which significantly influence the properties of the InSeSb system. With increasing Sb content, physical parameters such as the average coordination number, cross-linking density, mean bond energy, and cohesive energy were observed to increase. Theoretically calculated band gap values lie between 1.7 and 1.3 eV. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the alloys, revealing the coexistence of rhombohedral α-In2Se3 and orthorhombic Sb2Se3 phases. Energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing the presence of In, Se, and Sb in the bulk samples. Raman and FTIR spectroscopy further validated the presence of distinct structural units and molecular bonds as a function of Sb content, confirming the coexistence of α-In2Se3 and Sb2Se3 phases alongside In–Se, Se–Se, and Sb–Se bonds. A strong correlation was established between the experimental findings and theoretically calculated parameters, including the average coordination number, mean bond energy, glass transition temperature, cohesive energy, and optical band gap. This study provides a comprehensive insight into the compositional dependence of structural and physical properties in InSeSb chalcogenide alloys, enhancing our understanding of their potential applications.

Enhanced optical and electrical properties of PEO/PMMA/TiO2 nanocomposites for optoelectronic applications

In this study, we synthesized titanium oxide (TiO2) nanoparticles (NPs) via the sol-gel process and incorporated them into a polymer blend of polyethylene oxide (PEO) and polymethyl methacrylate (PMMA) to form PEO/PMMA/TiO2 nanocomposites. The TiO2 NPs were integrated into the polymer matrix using the casting method at varying concentrations (1, 2, and 3 wt.%). The structural, morphological, optical, and electrical properties of the prepared TiO2 and nanocomposite films were thoroughly characterized using techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and electrical impedance spectroscopy (EIS). TEM analysis revealed predominantly spherical TiO2 NPs with an average particle size of 15 nm. XRD and FTIR analyses confirmed the successful incorporation of TiO2 NPs and their interaction with the polymer chains, leading to modifications in the crystalline structure and chemical bonding of the nanocomposites. UV-Vis spectroscopy demonstrated a redshift in the absorption edge and increased absorbance with higher TiO₂ content, indicating enhanced optical properties. The indirect optical bandgap was observed to decrease from 4.19 eV to 2.21 eV as the TiO2 concentration increased, enhancing the material's photoresponsiveness. Additionally, the refractive index increased from 2.11 to 2.91, further supporting the potential for optical applications. EIS results showed a decrease in bulk resistance with increasing TiO2 concentration, suggesting improved electrical conductivity. These findings highlight the potential of PEO/PMMA/TiO2 nanocomposites for optoelectronic applications, where enhanced optical properties, such as improved light absorption, higher refractive index, and improved charge transport, are critical for device performance. The study offers an understanding of the PEO/PMMA/TiO2 nanocomposites, laying a foundation for future research in their applications in optoelectronic devices.

Comparative study of pure and chromium-doped nickel oxide nanoparticles synthesized by combustion synthesis for optoelectronic applications

Comparative study of pure and chromium-doped nickel oxide nanoparticles synthesized by combustion synthesis for optoelectronic applications

Comparison of the effect of gaseous and metallic additives on ultrathin Ag layer formation: An experimental and numerical investigation

Ultrathin Ag layers are promising for optoelectronic applications, however, the inherently poor wettability of Ag on oxide substrates such as SiOx poses a significant challenge. Current techniques for resolving this issue often introduce trace amounts of metallic or gaseous additives during Ag growth. Previous studies have not thoroughly compared the influence of metallic and gaseous additives on the wetting and optoelectrical performance of Ag. Even though these additives certainly improve Ag wetting, existing information on their effectiveness is inconsistent. In this study, we aimed to identify the most effective additive by investigating the impact of the O, N, Cu, and Zn additives on Ag wetting. We combined experimental and computational investigations to reveal the ways these additives at the Ag surface and/or the Ag − SiOx interface reduce the cohesive energy of the Ag layers, thereby determining the Ag wetting behavior. Consequently, our findings suggest that O is the most effective additive for improving the optoelectrical properties of the Ag layers owing to its ability to enhance Ag wettability and optoelectrical performance. This conclusion challenges conventional practices, heavily relying on metallic additives and Cu in particular. Our study provides valuable insights into the optimization of ultrathin Ag layers for optoelectronic applications.