Applications In Optoelectronic Devices Research Articles

Quadruple Stimuli-Responsive Behaviour of Acylhydrazone Crystals: Mechanical, Photomechanical, Thermomechanical, and Optical Waveguide Properties.

As society advances, the demand for high-performance crystal materials with versatile stimuli-responsive capabilities has increased. However, there remains a notable shortage of simple molecular crystals that exhibit stable and swift responses to various stimuli. In this study, we synthesized a novel acylhydrazone crystal by integrating benzene-fused heterocycles and halogens, achieving a crystal material with multiple stimuli-responsive behaviours. The crystal demonstrates good mechanical flexibility, capable of with standing a strain of 2.3 % under applying mechanical force and recovering its original shape after force removal. Crystal structure analysis reveals this property is due to the strong and flexible intermolecular interactions. It also exhibits rapid photomechanical bending away from light source under UV irradiation, which could be attributed to the facile photoisomerization. Moreover, the crystal undergoes significant thermomechanical transitions, including cracking and jumping, upon heating. Additionally, the prepared crystal exhibits passive optical waveguide of red light at 640 nm, which, combining the photomechanical bending, can achieve controllable light output direction. These multi-stimuli-responsive behaviors make the acylhydrazone crystal a promising candidate for applications in multifunctional sensors, optoelectronic devices, and thermal switches. This work provides a helpful reference for the study of potential crystal material design and functionality of advanced responsive systems.

Preparation and the Photoelectric Properties of ZnO-SiO2 Films with a Sol-Gel Method Combined with Spin-Coating.

This study explores the fabrication of ZnO-SiO2 composite films on silicon substrates via a sol-gel method combined with spin-coating, followed by annealing at various temperatures. The research aims to enhance the UV emission and photoelectric properties of the films. XRD showed that the prepared ZnO sample has a hexagonal structure. SEM images revealed the formation of ZnO nanorods within a dense SiO2 substrate, ranging from 10 μm to 30 μm in length. Photoluminescent analysis showed that the film exhibited strong UV emission centered at 360 nm. The response time measurements indicated that the optimal photoresponse time was approximately 2.9 s. These results suggest the potential of ZnO-SiO2 films as efficient UV-emitting materials with high photoconductivity and a stably reproducible response under visible light, thereby laying the foundation for their application in advanced optoelectronic devices.

Exploring the Impact of Elevated Pressure on the Structural Dynamics of TlInS2 Crystal (I): A First-Principles Investigation with XRD, Raman, and Hirshfeld Topology

The structural dynamics of Thallium Indium Disulfide (TlInS2) crystal under elevated pressures were comprehensively investigated using a combination of X-ray diffraction (XRD), Raman spectroscopy via first-principles calculations, and Hirshfeld surface (HS) analysis. This study aims to elucidate pressure-induced modifications in the crystal structure and their associated properties of TlInS2 crystal. The findings reveal significant structural transformations as pressure increases, with XRD patterns indicating lattice compression and a critical transition from semiconductor to conductor at pressure P=6.25GPa [42]. The calculations predict a reduction in bond lengths, specifically S1-In1 and S1-Tl2, alongside a corresponding decrease in lattice parameters and unit cell volume. Raman spectroscopy corroborates these changes through shifts in phonon modes. The HS analysis provides further insights into pressure-dependent alterations in intermolecular interactions, revealing changes in voids and surface characteristics. The data gained from TlInS2's structural behavior under pressure, contributing to the optimization of its functional properties for pressure-tunable applications in high-performance electronic and optoelectronic devices.

Efficient supercontinuum spectra by non-Gaussian pulses

Abstract In this article, we examine the generation of supercontinuum spectra using various non-Gaussian pulses in semiconductor quantum wells. Specifically, we employ weak probe pulses modulated by a strong optical beam, leveraging electromagnetically induced transparency within the system. Our findings indicate that the characteristics of supercontinuum generation, as compared to traditional Gaussian pulses, differ significantly when non-Gaussian pulses, such as sinh-Gaussian, cosh-Gaussian, and tanh-Gaussian pulses are being used. Notably, among the pulses studied, the cosh-Gaussian pulse achieves the broadest supercontinuum span, reaching ~21 μm, at the end of the semiconductor quantum well. These results suggest potential applications in optoelectronic and photonic devices designed for spectroscopic analysis.

Structural, electronic, optical, magnetic, and mechanical properties of SmMnO3 perovskite with europium and yttrium doping: A first-principles study

This paper explores the impact of europium (Eu) and yttrium (Y) doping on the electronic, magnetic, optical, elastic, and structural properties of SmMnO3 perovskites using the Quantum ESPRESSO code. The cohesive energy and tolerance factor calculations revealed that the perovskite can maintain structural stability up to 25% doping of Eu and Y. Bandgap calculations suggest that when Eu and Y are doped, the energy bandgap of pure SmMnO3 decreases significantly from 2.72 to 0.47 and from 2.72 to 0.76 eV, respectively. Doped SmMnO3 exhibits a UV shift and increased intensity in the absorption coefficient, while the reflectivity peak decreases. These changes in optical properties and bandgap due to Eu and Y doping make SmMnO3 a promising material for advanced applications in photovoltaics, UV photodetectors, and optoelectronic devices. The ferromagnetic property and total magnetic moment of SmMnO3 are found to be increased by Eu doping. Meanwhile, the magnetic moment gets reduced by Y doping. Curie temperature calculations indicate that Eu doping increases the Curie temperature from 255.35 to 314.28 K, while Y doping reduces it from 255.35 to 187.69 K. These changes in magnetic moment and Curie temperature suggest that the doped material is suitable to be used in magnetic sensors and storage devices. The calculated elastic constants, Young’s modulus, shear modulus, Poisson’s ratio, and B/G ratio suggest that both pristine and doped compounds under study show a ductile behavior.

Exploring the role of Germanium on the optoelectronic and thermoelectric response in making ductile lead-free perovskite halide using DFT

Abstract The structural instability observed owing to Sn2+ and the toxic effects of lead has prohibited the commercial use of all inorganic CsPb1-xSnxBr3 for optoelectronic memory device applications. In this work, we have inspected the structural, mechanical, electronic, optical, and thermoelectric response of all inorganic halide perovskite CsPb1-xGexBr3 (x = 0, 0.25, 0.50, 0.75, 1) to overcome the stability and toxicity of this optoelectronic resistive switching material using the full-potential linearized augmented-plane wave (FP-LAPW) technique grounded on density functional theory (DFT). Tran Blaha-modified Becky Johnson (TB-mBJ) approximation is used for the self-consistent field (SCF) calculations of considered halide perovskite CsPb1-xGexBr3. It is clear from the band structure that all compounds are semiconductors in nature. Moreover, the bandgap decreased with the increase in the concentration of Germanium (Ge) caused thebandgap tununig. The overall absorption of incident radiations increased and energy loss decreased with the increase in the concentration of doping, especially in the visible region. The thermoelectric properties have also been studied by using the BoltzTraP2 code. All the results computed physical properties confirmed the feasibility of these all-inorganic materials for their use in the fabrication of ductile, optical resistive switching memory RRAM devices.

First-principles pressure-dependent investigation of the physical and superconducting properties of ThCr2Si2-type superconductors SrPd2X2 (X = P, As).

The physical and superconducting characteristics of SrPd2P2 and SrPd2As2 compounds with applied pressure were calculated using density functional theory. The pressure effect on the structural properties of these compounds was investigated. The results show that both lattice constants and volume decrease almost linearly with increasing pressure. The elastic constants (C ij) for both compounds increase with increasing pressure and satisfy Born criteria for mechanical stability. The elastic parameters indicate the ductile behaviour and anisotropic nature of these compounds under applied pressure. The Debye temperature (ϴ D) and melting temperature (T m) increase with increasing pressure. The electronic band structure calculation of both compounds exhibits metallic characteristics at different pressures. The density of electronic states at the Fermi level, N(E F), consistently decreases as pressure increases, which is also reflected in the repulsive Coulomb pseudopotential (µ*), and the electron-phonon coupling constant (λ). These optical features suggest that both compounds are suitable for optoelectronic device applications. Furthermore, the superconducting transition temperature, T c, for both compounds is predicted to vary with applied pressure due to changes in ϴ D , N(E F), µ* and λ.

Investigation of different physical properties of mixed-halide double perovskites K2SnBr6-xClx and K2SnI6-xBrx (x = 0, 2, 4, 6) for optoelectronic device applications

Investigation of different physical properties of mixed-halide double perovskites K2SnBr6-xClx and K2SnI6-xBrx (x = 0, 2, 4, 6) for optoelectronic device applications

Study on the mechanism of enhancing photocurrent in TiS2 photodetector by vacancy- and substitution-doping

In materials lacking spatial inversion symmetry, the photovoltaic generation effect (PGE) manifests under polarized irradiation without the necessity of a p-n junction and demonstrates high polarization sensitivity across a broad spectrum. This characteristic presents significant potential for applications in low-power two-dimensional optoelectronic devices. In this study, we investigate the electronic structure, optical properties, and PGE in 2H-TiS2 by first-principles simulations, incorporating various types of point defects. We propose a mechanism to enhance photoconductivity in 2H-TiS2 by substitution doping and vacancy defects. When the photodetector is aligned along the armchair direction, the photocurrent exhibits a cosine dependency on the linear polarization angle. We achieved a remarkable enhancement in photocurrent, with a maximum value of 1.33 a20/photon, in contrast to only 0.11 a20/photon for the pure membrane. This improvement can be attributed to the introduction of point defects, which diminish the symmetry of the device and increase its asymmetry, thereby enhancing the photocurrent. Furthermore, we attained high polarization sensitivity, evidenced by a maximum extinction ratio of 262.4. Our findings not only propose an effective mechanism for enhancing PGE by substitution doping but also underscore the promising applications of the two-dimensional 2H-TiS2 monolayer in optoelectronics, particularly in photoelectric detection.

Probing the opto-electronic, thermoelectric, thermodynamic and elastic responses of lead-free double perovskite Li2ATlCl6 (A = Na and K) for potential photovoltaic and high- energy applications: A DFT study

The physical properties of double halide perovskite Li2ATlCl6 (A = Na and K) were examined through a first-principles study and semi-classical Boltzmann theory using the WEIN2k package, focusing on renewable energy generation and solar cell applications. Research on halides is growing within the optoelectronics and thermoelectric field and is anticipated to meet energy shortage demands. The volume-energy diagram confirms their structural stability, while the Pugh and Poisson ratios suggest ductility based on their elastic properties. The electronic properties were analyzed, and bandgaps were calculated using modified Becke-Johnson (mBJ) potentials, yielding bandgaps of 3.51 eV and 2.97 eV for Li2ATlCl6 (A = Na and K) respectively. The optical properties, evaluated using complex dielectric functions, indicated optimal light absorption in the infrared (IR) regions. Additionally, the thermoelectric (TE) properties of Li2ATlCl6 (A = Na and K) were analyzed using semi classical Boltzmann theory with a constant relaxation time approximation. At 1200 K, the calculated figures of merit (ZT) values were 0.75 and 0.69, respectively, indicating their potential for thermoelectric applications. Also, the thermodynamic properties are computed under pressure (0–15 GPa) and temperature (0–1200 K). These investigations offer a profound comprehension of these materials for their further employment. These results highlight their potential for optoelectronic device applications and are expected to encourage further experimental research on the feasibility of Li2ATlCl6 (A = Na and K) for optical devices.

Controlled synthesis of branched 2D polytypic CdS quantum nanostructures

Colloidal two-dimensional (2D) semiconductor quantum nanostructures have attracted substantial interest owing to their atomically uniform thickness and spectrally sharp luminescence, exhibiting potential for optoelectronic and electronic device applications. Despite recent advancements in chemical synthesis enabling better control over lateral shapes and heterostructures, achieving morphological complexity in 2D semiconductor nanocrystals remains challenging. In this study, we report the controlled synthesis of branched 2D CdS quantum nanostructures, facilitating the realization of polytypism by growing zinc blende nano-domains within wurtzite-structured quantum nanoplates. The synthesized structures comprise multi-branched 2D quantum nanoplate arms with a precisely controlled thickness of ∼1.8 nm, joined at the zinc blende nano-domain junctions. The reaction conditions enable controlled variation in the length and complexity of these structures, while maintaining their sharp excitonic features of quantum-confined 2D semiconductor nanocrystals. In-situ small- and wide-angle X-ray scattering analysis, combined with spectroscopic and microscopic analyses, reveals that a discontinuous increase in thickness beyond a certain threshold is necessary to form zinc blende crystals within wurtzite nanoplates, upon which additional 2D quantum nanoplates subsequently grow. This study advances our understanding of 2D nanocrystal synthesis mechanisms and provides pathways for designing and fabricating branched 2D nanostructures with tailored properties.

Multimode Luminescence Tailoring in PMA4Na(In,Sb)Cl8 Organic-inorganic Hybrid Metal Halide via Rigid Benzene Ring Induced Local Lattice Distortion.

Low dimensional organic-inorganic hybrid metal halide materials have attracted extensive attention due to their superior optoelectronic properties. However, low photoluminescence quantum yields (PLQYs) caused by parity-forbidden transition hinder their further application in optoelectronic devices. Herein, a novel yellow-emitting PMA4Na(In,Sb)Cl8 (C7H10N+, PMA+) low-dimensional OIMHs single crystal with a PLQY as high as 88 % was successfully designed and synthesized, originating from the fact that the doping of Sb3+ effectively relaxes the parity-forbidden transition by strong spin-orbit (SO) coupling and Jahn-Teller (JT) interaction. The as-prepared crystal shows an efficient dual emission peaking 495 and 560 nm at low temperature, which are ascribed to different levels of 3P1→1S0 transitions of Sb3+ in [SbCl6]3- octahedral caused by JT deformation. Moreover, wide-range luminescence tailoring from cyan to orange can be achieved through adjusting excitation energy and temperature because of flexible [SbCl6]3- octahedral in the PNIC lattice. Based on a relative stiff lattice environment, the 560 nm yellow emission under 350 nm light excitation exhibits abnormal anti-thermal quenching from 8 to 400 K owing to the suppression of non-radiative transition. The multimode luminescence regulation enriches PMA4Na(In,Sb)Cl8 great potential in the field of optoelectronics such as temperature sensing, low temperature anti-counterfeiting and WLED applications.

Investigation of optical and thermoelectric characteristics of novel zintl-phase alloys CaZn2X2 (X = P, As, Sb) for green energy applications

Abstract This study examines the photovoltaic and thermoelectric response of calcium-based novel Zintl-phase alloys CaZn2X2 (X = P, As, Sb). The structural, optoelectronics, and transport features of Zintl CaZn2X2 (X = P, As, Sb) compounds have been analyzed using the full potential linearized augmented plane wave (FPLAPW) technique. Investigations on formation energy and phonon dispersion have confirmed the formation and dynamical stabilities. These compounds exhibit a semiconductor behavior, as their predicted bandgap values: 1.76 eV for CaZn2P2, 1.14 eV for CaZn2As2, and 0.32 eV for CaZn2Sb2. By investigating the optical properties, we have discovered their potential applicability in optoelectronic and photovoltaic devices, as evidenced by the optical response of these phases. The traditional Boltzmann transport theory has assessed transport characteristics against temperature and chemical potential. Significantly higher values of the Seebeck coefficient are achieved at room and elevated temperatures. Moreover, the power factor demonstrates a linear relationship with rising temperature. The remarkable optoelectronic properties and exceptional power factor values suggest that these materials are suitable for deployment in photovoltaic and transport devices.

Electronic and optical properties of InSe/CuI van der Waals heterostructure with type-II band alignment: Effects of vertical strain and electric field

Van der Waals (vdW) heterostructures enable the design of novel two-dimensional (2D) materials with customized properties, offering opportunities for creating unique optoelectronic devices. The type-II band alignment in vdW heterostructures can result in the formation of interlayer excitons (IXs) with long lifetimes, providing a crucial platform for long-lived excitonic devices. Motivated by the recent success in synthesizing the InSe and CuI monolayers, we designed a novel vdW heterostructure from the monolayers. Our results based on the many-body perturbation theory reveal that the InSe/CuI vdW heterostructure is a semiconductor with type-II band alignment, forming an IX with a binding energy of 0.50eV. The observed IX is robust against changes in stacking configuration and even spin–orbit coupling, making the heterostructure a potential candidate for the development of optoelectronic devices. Furthermore, we show that the band gap of the heterostructure is sensitive to external electric fields, so that, a transition from semiconductor to metal occurs by applying an appropriate electric field. Interestingly, the band gap of the heterostructure increases linearly by applying vertical strain. Our findings suggest that the InSe/CuI vdW heterostructure is a very promising candidate for application in optoelectronic devices.

Is There an Optimal Spacer Cation for Two-Dimensional Lead Iodide Perovskites?

Two-dimensional lead iodide perovskites have attracted significant attention for their potential applications in optoelectronic and photonic devices due to their tunable excitonic properties. The choice of organic spacer cations significantly influences the light emission and exciton transport properties of these materials, which are vital for their device performance. In this Perspective, we discuss the impact of spacer cations on lattice dynamics and exciton-phonon coupling, focusing on three representative 2D lead iodide perovskites that exhibit distinct types of structural distortions. Minimizing structural distortions, such as dynamic out-of-plane octahedral tilting and lone pair distortion, appears to be essential for achieving narrow photoluminescence (PL) emission peaks, high PL quantum yields, and rapid exciton diffusion by suppressing exciton-phonon coupling, as demonstrated in 2D perovskites based on phenylethylammonium cation or its derivatives. We propose that designing spacer cations with enhanced intermolecular interactions and denser packing, combined with the close packing of inorganic ions to minimize the motions of both organic and inorganic lattices, would be the ideal scenario for yielding the most favorable optoelectronic properties in these materials.

Decisive role of organic fluorophore and surface defect state in the photoluminescence of carbon quantum dots

Carbon quantum dots (CQDs) hold significant promise for applications in biological imaging, sensing, and optoelectronic devices owing to their superior photostability and low toxicity. Nevertheless, the elucidation of their photoluminescence mechanism remains an open question, necessitating further comprehensive investigation. In this Letter, CQDs exhibiting ultraviolet (UV) and white fluorescence were isolated through silica gel column chromatography separation of the crude product obtained from a one-step solvothermal synthesis. CQDs with different luminescent properties exhibit the same crystal structure and similar particle size distributions. Both CQDs exhibit orthorhombic structure where C60/C70 molecules are located at lattice points, having average particle sizes of 2.71 and 2.98 nm, respectively. Consequently, the luminescent properties of the synthesized CQDs are predominantly governed by their surface structure. The results of microstructure characterization and spectroscopic analysis demonstrate that the UV emission originates from the C(=O)OH and C–O–C related luminescent moieties within organic fluorophores, and the blue emission band is attributed to defect states related to surface group C–O–C, while the green/yellow emission arises from C(=O)O related surface defect levels. These observations have gained a profound understanding of the luminescent genesis of CQDs, broadened the luminescence coverage wavelength range of CQDs, and enriched the family of CQDs materials.

Excitonic-Vibrational Interaction at 2D Material/Organic Molecule Interfaces Studied by Time-Resolved Sum Frequency Generation.

The hybrid heterostructures formed between two-dimensional (2D) materials and organic molecules have gained great interest for their potential applications in advanced photonic and optoelectronic devices, such as solar cells and biosensors. Characterizing the interfacial structure and dynamic properties at the molecular level is essential for realizing such applications. Here, we report a time-resolved sum-frequency generation (TR-SFG) approach to investigate the hybrid structure of polymethyl methacrylate (PMMA) molecules and 2D transition metal dichalcogenides (TMDCs). By utilizing both infrared and visible light, TR-SFG can provide surface-specific information about both molecular vibrations and electronic transitions simultaneously. Our setup employed a Bragg grating for generating both a narrowband probe and an ultrafast pump pulse, along with a synchronized beam chopper and Galvo mirror combination for real-time spectral normalization, which can be readily incorporated into standard SFG setups. Applying this technique to the TMDC/PMMA interfaces yielded structural information regarding PMMA side chains and dynamic responses of both PMMA vibrational modes and TMDC excitonic transitions. We further observed a prominent enhancement effect of the PMMA vibrational SF amplitude for about 10 times upon the resonance with TMDC excitonic transition. These findings lay a foundation for further investigation into interactions at the 2D material/organic molecule interfaces.

Water Hyacinth as a Renewable Source of Cellulose Nanofibers: Fabrication and Properties of Optically Transparent Nanocomposites

ABSTRACT Due to its rapid reproduction, high cellulose content, and low lignin proportion, water hyacinth (Eichhornia crassipes) is a sustainable raw material for preparing cellulose nanofibers (CNFs). We extracted CNFs from water hyacinth and used them to fabricate nanopapers. Transparent nanocomposites were subsequently developed by immersing the CNF-derived nanopapers in acrylic resins. These nanocomposites exhibited promising mechanical properties and optical transparency. Compared with neat acrylic films, the nanocomposites exhibited a 13.5-fold improved tensile strength, an 80-fold increased Young’s modulus, and similar tensile strain. These considerably increased mechanical properties were attributed to strong interfacial bonding between the acrylic resin and CNF nanopaper, estimated by the rule of mixtures. Moreover, the CNF nanopaper significantly decreased the coefficient of thermal expansion of the acrylic resin from 192.3 to 16.3 ppm K−1, which is comparable to that of borosilicate glass. The outstanding properties of these nanocomposites render them suitable for applications in flexible optoelectronic devices, such as organic light – emitting diode displays and solar cells.

Evaluating the impact of microstructure modifications on thin film photoelectric properties

Microstructure modifications on thin photoelectrical properties refers to changes in the microscopic structure of thin films that affect their ability to convert light into electricity. This study investigates the deposition and post-treatment effects in the electric and visual qualities of GZO, IZO, and ZnO thin layers, aiming to enhance their applicability in electronic and optoelectronic devices, according to the X-raydiffraction (XRD) examination. Thin films were deposited on glass substrates using magnetic sparking at thicknesses of 300 nm and 500 nm, followed by treatments like wet aging and annealing at 220 °C. The results showed significant improvements in crystallinity and optical characteristics, with ZnO films exhibiting a preferred (003) orientation. IZO films demonstrated notable mobility at 10.96 cm2/V-sec and resistivity of 2.49×10⁻3 ohm-cm. The novelty of this research is the novel integration of wet aging and low-temperature annealing, that notably improves thin film efficiency while maintaining structural integrity. The findings indicate that post-treatment significantly enhances the properties of these thin films, suggesting their potential for various electronic applications.

Optical properties of Gd3+ doped bismuth silicate crystals based on first principles

Bismuth silicate (Bi4Si3O12, BSO) crystal, as a nonlinear optical material with excellent optical properties, has a wide range of applications in laser technology, optical communication, and optical information processing. In order to further improve its performance, this study adopts a first principles calculation method based on density functional theory (DFT), selects Gd3+ as the dopant, and calculates and explores the changes in optical properties of BSO crystals after doping with 1/12, 1/6, and 1/3Gd3+. The calculation results show that the doping of Gd3+ changes the electronic structure of BSO crystals, which is manifested in the emergence of new light absorption and emission characteristics, an increase in carrier concentration, an improvement in conductivity, and an enhancement of crystal polarization ability in optical properties. In addition, doping with Gd3+ increases the light transmission rate and reduces energy loss of BSO crystals, while releasing more energy during electron band transitions, effectively improving the luminescence performance of BSO crystals. The theoretical research in this article provides an important theoretical basis for understanding the influence of Gd3+ doping on the optical properties of BSO, and by optimizing the ratio of Gd3+, the optical properties of BSO can be further regulated, opening up new possibilities for its application in optoelectronic devices.