Applications In Optoelectronic Devices Research Articles

Detailed structural study, optical, and dielectric properties of Co0.4Ni0.3Zn0.3Fe2O4 ferrite and its potential applications for optoelectronic and electronic devices

Detailed structural study, optical, and dielectric properties of Co0.4Ni0.3Zn0.3Fe2O4 ferrite and its potential applications for optoelectronic and electronic devices

Optical properties of quasi-two-dimensional GaAs/AlGaAs nanosheets prepared by releasing epitaxial layer.

Quasi-two-dimensional nanosheets exhibit novel properties and promising applications in optoelectronic flexible devices. Research on non-layered III-V semiconductor nanosheets has been constrained by their covalent bonding connections. In this study, GaAs/AlGaAs heterojunction nanosheets were prepared by releasing an epitaxial layer, and their optical properties were investigated by adopting steady-state and transient absorption spectroscopy. The optical properties of the independent GaAs/AlGaAs heterojunction were investigated separately in order to exclude the effect of the substrate. This work provides a comprehensive understanding of the physics of III-V semiconductor quasi-two-dimensional nanosheets.&#xD.

Precise Tailoring of Unprecedent Layered Perovskite-type Heterostructure Ferroelectric via Chemical Molecular Scissor.

Precise stacking of distinct two-dimensional (2D) rigid slabs to build heterostructures has renewed the portfolio of 2D materials, e.g., magic-angle graphene, due to the emergence of exotic physical properties. Recently, single-crystal heterostructures of layered perovskites have emerged as an exciting branch, while it remains scarce to achieve strong ferroelectricity in this new heterostructure family. Here, we present the first ferroelectric of 2D perovskite heterostructures as single crystal, (EA3Pb2Br7)EA4Pb3Br10 (1, EA = ethylamine), by precisely tailoring inorganic sheets via a chemical molecular scissor. It has notable ferroelectricity of large spontaneous polarization (Ps ~ 5.0 μC/cm²) and high Curie temperature (Tc ~ 375 K). Structurally, its inorganic framework adopts a unique 2D heterostructure that contains two different rigid slabs of {EA3Pb2Br7}n and {EA4Pb3Br10}n. This motif is self-assembled by layer-by-layer clipping of rigid prototype sheets, using extra neopentylamine as a molecular chemical scissor. Unlike epitaxial growth, such a molecule-level stacking facilitates the growth of heterostructure single crystals. Combining its strong ferroelectricity and inherent anisotropy, crystal-based device of 1 exhibits an ultrahigh polarized-light sensitivity up to ~37 in self-powered mode, being the highest level of 2D perovskite ferroelectric family. Our work will facilitate the further development of ferroelectric materials for optoelectronic device applications.

2D MXenes: Synthesis, Properties, and Applications in Silicon-Based Optoelectronic Devices.

MXenes, a rapidly emerging class of 2D transition metal carbides, nitrides, and carbonitrides, have attracted significant attention for their outstanding properties, including high electrical conductivity, tunable work function, and solution processability. These characteristics have made MXenes highly versatile and widely adopted in the next generation of optoelectronic devices, such as perovskite and organic solar cells. However, their integration into silicon-based optoelectronic devices remains relatively underexplored, despite silicon's dominance in the semiconductor industry. In this review, a timely summary of the recent progress in utilizing Ti-based MXenes, particularly Ti3C2Tx, in silicon-based optoelectronic devices is provided. The composition, synthesis methods, and key properties of MXenes that contribute to their potential for enhanced device performance are focused on. Furthermore, the latest advancements in MXene applications in silicon-based solar cells and photodetectors are discussed from fundamental and applied perspectives. Finally, the key challenges and future opportunities for the integration of MXenes in silicon-based optoelectronic devices are outlined.

Effect of Ti Doping on the Structural, Electronic, Optical and Thermoelectric Properties of ZrO2: A Systematic DFT Approach

AbstractIn this work, the density functional theory (DFT) calculations in wien2k code to investigate the effect of (Titanium) Ti doping (25% and 50%) in ZrO2 is utilized. The negative values of the Ef, i.e., −2.14, −3.42 and −2.31 as well as energy versus volume curves show the stability of pure, 25% and 50% doped ZrO2. From band structure and density of states results it is confirmed that upon doping Ti, the band gap of ZrO2 become direct from indirect and reduces from 3.10 eV to 1.26(25% doped)/1.16(50% doped). The optical investigations reveal that incorporation of Ti improved the optical properties significantly, which show the significance of these materials for optoelectronic device applications. The thermoelectric properties are investigated using the Boltzmann transport theory. The Seebeck coefficient, electronic conductivity, thermal conductivity, power factor and figure of merit is calculated. The obtained results show that the under study compounds are best candidates for different thermoelectric applications.

Molecular engineering charge transfer and triplet exciton formation in donor-acceptor cocrystals.

Organic donor-acceptor (D-A) cocrystals are gaining attention for their potential applications in optoelectronic devices. This study explores the dynamics of charge transfer (CT) and triplet exciton formation in various D-A cocrystals. By examining a series of D-A cocrystals composed of coronene (COR), peri-xanthenoxanthene (PXX), and perylene (PER) donors paired with N,N-bis(3'-pentyl)perylene-3,4:9,10-bis(dicarboximide) (PDI), naphthalene-1,4:5,8-tetracarboxy-dianhydride (NDA), or pyrene-4,5,9,10-tetraone (PTO) acceptors, using transient absorption microscopy and time-resolved electron paramagnetic resonance spectroscopy, we find that the strength of the CT interaction influences the nature and yield of triplet excitons produced by CT state recombination. In particular, in the PER-PDI, COR-PTO, and PER-PTO cocrystals, localized triplet excitons are lower in energy than the CT state. By contrast, no localized triplet excitons are available to the CT states of the PXX-NDA, PER-NDA, and PXX-PTO cocrystals, and as a result, the CT states rapidly decay to ground state with no triplet formation. Moreover, density functional theory calculations show that the transition between delocalized CT states to a triplet state localized to a single donor or acceptor unit provides the source of spin-orbit coupling necessary when the triplet states are energetically accessible. These findings provide insights into the design of molecular materials with tailored exciton properties for optoelectronic applications.

Electrically Switching Ferroelectric Order in 3R-MoS2 Layers.

Transition metal dichalcogenides (TMDs) with rhombohedral (3R) stacking order are excellent platforms to realize multiferroelectricity. In this work, we demonstrate the electrical switching of ferroelectric orders in bilayer, trilayer, and tetralayer 3R-MoS2 dual-gate devices by examining their reflection and photoluminescence (PL) responses under sweeping out-of-plane electric fields. We observe sharp shifts in excitonic spectra at different critical fields with pronounced hysteresis. These phenomena are attributed to distinct interlayer polarizations resulting from specific lateral displacements between the layers, with each configuration yielding a unique ferroelectric state. Our findings indicate two, three, and four ferroelectric regimes for bilayer, trilayer, and tetralayer structures, respectively, in agreement with theoretical prediction. Moreover, each polarization state can be stabilized at zero applied electric field. The tunable ferroelectric phases of these multilayers pave the way for innovative applications in non-volatile memory, logic circuits, and optoelectronic devices.

Recent progress in two-dimensional polymer materials: interfacial synthesis and applications

Abstract As a new two-dimensional polymer synthetic material, two-dimensional polymers (2DPs) not only have the advantages of high specific surface area and high transparency of two-dimensional materials, but also have the advantages of high mechanical strength and easy processing of polymer materials. Therefore, 2DPs are widely used and have become one of the indispensable materials today. However, there are still challenges in preparing 2DPs using traditional methods. Among the various synthesis strategies, the interfacial synthesis methods with the advantages of simple operation and high crystallinity have become typical method for preparing 2DPs. In this review, we first summarize the types of interface synthesis methods and the latest research progress. Secondly, the 2DPs applications in optoelectronic devices, membrane separation, sensor, electrical device and batteries, etc. are introduced. Finally, we summarize and prospect the existing challenges and future research directions based on the current research status of 2DPs.

Study on the modulation mechanism of the optoelectronic properties based on common electrode metal atom adsorption on graphene/MoTe2.

The two-dimensional graphene/MoTe2 heterostructure holds extensive potential applications in optoelectronic devices, sensors, and catalysts. To expand its optical applications, this study systematically investigates the adsorption stability of metal atoms (Au, Pt, Pd, and Fe) on the graphene/MoTe2 and their influence on its optoelectronic properties employing first-principles methods. The findings indicate that after the adsorption of Au and Pd, the structure retains its direct bandgap properties, while the adsorption of Pt and Fe exhibits indirect bandgap characteristics. The work functions for all adsorbed structures are lower compared to the pristine graphene/MoTe2. The total density of states is primarily derived from the C-2p, Mo-4d, Te-5p orbitals, as well as the d and s orbitals of the adsorbed atoms. The pristine graphene/MoTe2 exhibits significant absorption in the ultraviolet range. Once graphene/MoTe2 is adsorbed by metal atoms, it can significantly enhance the optical absorption across the spectrum from infrared to ultraviolet light. These findings provide important theoretical guidance for regulating the application of graphene/MoTe2 in optoelectronics and related fields. All analyses are grounded in density functional theory first principles and computed using CASTEP. Graphene/MoTe2 consists of 4 × 4 × 1 single-layer, graphene single layer, and 3 × 3 × 1 single-layer MoTe2. To prevent interactions between neighboring unit cells, a 20Å vacuum space in the z-direction is employed. The electronic exchange-correlation interactions are treated using the Perdew-Burke-Ernzerhof functional within the framework of the generalized gradient approximation. Van der Waals (vdW) interactions are incorporated using the vdW correction function proposed by Grimme, which effectively describes vdW interactions. During the simulation, the cutoff energy for plane wave expansion is set to 420eV, and the k-point grid is set to 4 × 4 × 1. The atomic displacement convergence standard is 0.002Å, the internal stress convergence standard is 0.1GPa, and the interaction force convergence standard between atoms is 0.05eV/Å. The convergence threshold for the iteration precision is set to ensure that the total energy for each atom is not less than 2 × 10-5eV/atom.

Raman and Photoluminescence Studies of Quasiparticles in van der Waals Materials.

Two-dimensional (2D) layered materials have received much attention due to the unique properties stemming from their van der Waals (vdW) interactions, quantum confinement, and many-body interactions of quasi-particles, which drive their exotic optical and electronic properties, making them critical in many applications. Here, we review our past years' findings, focusing on many-body interactions in 2D layered materials, including phonon anharmonicity, electron-phonon coupling (e-ph), exciton dynamics, and phonon anisotropy based on temperature (polarization)-dependent Raman spectroscopy and Photoluminescence (PL). Our review sheds light on the role of quasi-particles in tuning the material properties, which could help optimize 2D materials for future applications in electronic and optoelectronic devices.

Enhanced Red Luminescence in Dy3+/Eu3+Co-doped Calcium Alumino Borosilicate Glasses for w-LED Applications.

Dy3+ and Eu3+ co-doped borosilicate glasses have been synthesised via melt quench technique. Amorphous behaviour of the sample has been verified by XRD study. FT-IR analysis confirmed the presence of various bonds in the host lattice. Energy band gap values of the co-doped glasses were estimated from the UV-VIS data via Tauc Plot. Excitation spectra were recorded under 575nm (Dy3+) and 612nm (Eu3+) emission wavelengths of co-doped glasses. Emission spectra of the co-doped glasses under 350nm and 393nm showed a significant shift towards increasing red emission with increasing Eu3+ concentrations. Dexter's theory was applied to study the transfer of energy mechanism between Dy3+ and Eu3+ ions. Time decay curves were plotted for the co-doped glasses for 350nm excitation and 576nm emission wavelength. CIE coordinate diagram shows a shift towards red region with increasing excitation wavelength from 350nm to 465nm. The enhancement of red component with increasing Eu3+ concentrations in the as -prepared borosilicate glasses can be appropriately utilised in various w-LEDs and other optoelectronic devices applications.

Single-Walled ZnSe Nanotubes for High-Performance Photodetectors: A Computational Prediction.

Low-dimensional nanomaterials show great potential for developing semiconducting materials due to their distinct electronic,optical, and mechanical properties. In this study, we constructed various one-dimensional ZnSe nanotubes and investigated their transport and photoresponse properties by using the density functional theory (DFT) and non-equilibrium Green's function (NEGF) method. Under bias regulation, one-dimensional tetragonal ZnSe nanotube curled along the diagonalcan reach a current of 111.3 μA at a bias of 4.0 eV. It is worth noting that for all considered photon energies, thephotocurrent exhibits a cosine dependence on the polarization angle, which is consistent with the photogalvanic effect. The results show that our constructed ZnSe nanotubes have potential for applications in electronic and optoelectronic devices.

The optoelectronic properties of boron nitride nanotubes of armchair (7, 7) and zigzag (12, 0) types: A theoretical study

In this article, the electronic and optical properties of single-walled boron nitride nanotubes (SWBNNTs) in zigzag (12, 0) and armchair (7, 7) configurations were examined using density functional theory (DFT) with the Vienna Ab initio Simulation Package (VASP). The analysis shows that SWBNNTs exhibit electronic characteristics with a density of states and an electronic band gap around 4 eV. Regarding optical properties, the calculations reveal key features such as absorption, reflection, and dielectric constant, with a notably strong absorption peak in the ultraviolet region. These results highlight the potential of SWBNNTs for applications in optoelectronic devices.

Thickness-dependent surface reconstructions in non-van der Waals two-dimensional materials.

Bismuth oxychalcogenides (Bi2O2X, X = S, Se, Te), a family of non-van der Waals (non-vdW) two-dimensional (2D) semiconductors, are attracting significant attention due to their outstanding semiconducting properties and huge potential in various applications of electronic and optoelectronic devices. Surface imperfections (e.g., surface vacancies) and surface reconstructions are more likely to appear and may cause intriguing physical properties and novel phenomena in the non-vdW 2D materials than the vdW cases. Here, we explore the impacts of surface vacancies and surface reconstructions on the properties of the surfaces and 2D structures of Bi2O2X by using the first-principles method. We find that the dimerization of surface X-vacancies occurs in Bi2O2S and Bi2O2Te (001) surfaces, like that happening in Bi2O2Se. Unexpectedly, the electronic structures of Bi2O2X (001) surfaces show strong tolerance to the order of surface X-vacancies. Furthermore, we find a phenomenon of thickness-dependent surface reconstructions for non-vdW Bi2O2X ultrathin films. For a monolayer, the zipper-surface is more stable, while the dimer-surface is generally more stable for thicker films. Calculated exfoliation energies of the Bi2O2X monolayer and multi-layers are close to those of common vdW 2D materials, indicating that 2D Bi2O2X belong to easily fabricated 2D materials, even though the inter-layer binding interaction is of the non-vdW type. Our results suggest that non-vdW 2D materials can possess intriguing properties because of surface imperfections and reconstructions in comparison with vdW 2D materials.

Ultrahigh carrier mobility and multidirectional piezoelectricity in 2D Janus copper-containing chalcogenide monolayers.

Two-dimensional (2D) materials have attracted enormous research attention due to their remarkable properties and potential applications in electronic and optoelectronic devices. In this work, Janus 2D copper-containing chalcogenides, CuP2Se0.5S0.5 and CuP2Te0.5Se0.5 monolayers, are proposed and studied systematically based on first-principles calculations. These two Janus-structured materials possess the same thermal and dynamic stability as the perfect CuP2Se structure. Remarkably, we observe multiple VBM and CBM points with negligible energy differences in the band structures of perfect CuP2Se and Janus CuP2Se0.5S0.5 and CuP2Te0.5Se0.5 monolayers. This will significantly impact the electronic and transport properties of the material. The calculated anisotropic carrier mobilities can reach 104-105 cm2 V-1 s-1 orders of magnitude, which are higher than those of most reported materials. Meanwhile, the two Janus derivatives, CuP2Se0.5S0.5 and CuP2Te0.5Se0.5 monolayers, exhibit outstanding multidirectional piezoelectricity, which are comparable with those of traditional piezoelectric materials. The combination of ultrahigh carrier mobility and multidirectional piezoelectricity indicates that these novel 2D Janus materials could be promising for applications in electronic and piezoelectric devices under special conditions.

Adding multiple electrons to helicenes: how they respond?

Helicenes of increasing dimensions and complexity have recently burst into the scene due to their unique structures coupled with interesting chiral, optical, and conducting properties. The helicene-related research has quickly progressed from fundamental curiosity to a diverse range of applications in organic catalysis, optoelectronic devices, chiroptical switches, sensors, and energy storage. The in-depth understanding of electron accepting properties of helicenes should further advance their materials chemistry applications, however, previous reports only relied on spectrocopic and electrochemical studies, while their structural changes weren't extensively discussed. Therefore, we initiated a broad investigation of chemical reduction behaviour of helicenes ranging in size and properties coupled with X-ray diffraction characterization of the reduced products. The responses of helicenes with different structures to the stepwise electron addition were investigated using a combination of X-ray crystallography, spectroscopic methods, and calculations. This study revealed topology- and charge-dependent consequences of chemical reduction ranging from reversible geometry perturbation to irreversible core transformation and site-specific reactivity of helicenes in addition to original alkali metal coordination patterns. This overview is focused on the crystallographically confirmed examples stemming from chemical reduction reactions of different helicenes with alkali metals. The opened discussion should stimulate further exploration of reactivity and complexation of novel π-expanded and heteroatom-doped helicenes based on the revealed structure-property correlations, thus advancing their applications as intriguing new materials.

Analysis of the structural and optical characteristics of ZnSe thin films as interface layer

This research reveals the results of a comprehensive analysis of the optical and structural features of zinc selenide (ZnSe) thin film. The studied film was synthesized using the thermal evaporation method after preparation on the glass substrate. The film’s structural characteristics, which have been determined by using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD), confirm the polycrystalline nature of the films with a predominant cubic zinc-blende structure. The surface morphology investigated through SEM reveals a uniform grain distribution with minimal surface defects, indicating high-quality film formation. In order to examine the optical characteristics, the ultraviolet–visible spectroscopy method is used in a spectral range between 300 and 900 nm. In this way, the ultraviolet–visible spectroscopy data are utilized to obtain optical features such as extinction coefficient (k), optical band gap (Eg), refractive index (n), absorption coefficient (α), and optical conductivity (σopt). These optical properties are assessed using ultraviolet–visible spectroscopy, revealing a direct band gap of approximately 2.88 eV, which is consistent with the bulk properties of ZnSe and suitable for optoelectronic applications. The results of this study clearly show that the studied ZnSe film can be used for optoelectronic device applications.

Identification of Two-Dimensional Interlayer Excitons and Their Valley Polarization in MoSe2/WSe2 Heterostructure with h-BN Spacer Layer.

Interlayer excitons (IXs) in the heterostructure of monolayer transition metal dichalcogenides (TMDs) are considered as a promising platform to study fundamental exciton physics and for potential applications of next generation optoelectronic devices. The IXs trapped in the moiré potential in a twisted monolayer TMD heterostructure such as MoSe2/WSe2 form zero-dimensional (0D) moiré excitons. Introducing an atomically thin insulating layer between TMD monolayers in a twisted heterostructure would modulate the moiré potential landscape, thereby tuning 0D IXs into 2D IXs. However, the optical characteristics of IXs have not been elucidated. Here, we have experimentally investigated the significant optical characteristics arising from IXs in a MoSe2/h-BN/WSe2 heterostructure by optical spectroscopy. The experimental results of time-resolved photoluminescence spectroscopy combined with phenomenological rate equation analysis reveal that the radiative decay rate of IXs in the MoSe2/h-BN/WSe2 heterostructure changes as a function of temperature, which strongly suggests the emergence of 2D IXs by the modulation of potential. Moreover, we demonstrate the valley polarization arising from the prolonged valley relaxation lifetime of 2D IXs reaching 100 ns at low temperature, which is dominated by electron-hole exchange interactions. These findings provide us with an effective strategy to tailor the dimensionality of IXs and elucidate the desired optoelectronic response of IXs in monolayer semiconductor heterostructures.

Insight into the optoelectronic and thermoelectric properties of novel LaSeM (M = Cl, F) chalcohalide semiconductors: ab-initio study

Abstract Chalcohalide materials demonstrate extraordinary thermal capacity and adjustable optoelectronic properties. Here we used the density functional theory and studied the structural, electronic, optical, and thermoelectric properties of novel LaSeM (M = Cl, F) ternary chalcohalides. The formation energies of LaSeCl and LaSeF were determined to be −2.21 (eV/f. u) and −2.32 (eV/f. u), respectively. The cohesive and formation energies well impacted the stable nature and phase transition features of these materials. The studeid materials were predicted to have a direct band gap nature as observed from the band structure investigation. For LaSeCl material, the projected band gaps as determined by the PBE-GGA and TB-mBJ potentials are 1.41 eV and 1.95 eV, whereas for the LaSeF the values are 1.72 eV and 2.36 eV, respectively. The complex dielectric function along with the other noteworthy optical parameters are computed for their potential applications in optoelectronics devices. The spectral region with a negative value of ε 1(ω), suggests these materials to have a metallic behavior. The predicted negative Seebeck coefficient values throughout the temperature range for LaSeCl and LaSeF materials display n-type conduction behavior. LaSeF exhibits more noticeable temperature-dependent improvements in electrical conductivity compared to LaSeCl.

Reconfigurable Phototransistors Driven by Gate-Dependent Carrier Modulation in WSe2/Ta2NiSe5 van der Waals Heterojunctions.

Reconfigurable field-effect transistors (RFETs) offer notable benefits on electronic and optoelectronic logic circuits, surpassing the integration, flexibility, and cost-efficiency of conventional complementary metal-oxide semiconductor transistors. The low on/off current ratio of these transistors remains a considerable impediment in the practical application of RFETs. To overcome these limitations, a van der Waals heterojunction (vdWH) transistor composed of WSe2/Ta2NiSe5 has been proposed. By modulating a single back-gate voltage and source-drain voltage inputs, the transistor achieves a switchable polarity configuration and bidirectional rectification, making it capable of functioning as a gate-controlled bidirectional half-wave rectifier. The proposed RFET exhibits tunable positive/negative photovoltaic responses, advanced optoelectronic performance, and a gate-voltage-dependent reversal of the photodetector position. Detailed energy band diagram studies have shown that the reconfigurability of the device arises from carrier blockage resulting from the type-I band structure and carrier injection modulated by gate-dependent Schottky barriers. Consequently, the reconfigurable WSe2/Ta2NiSe5 vdWH holds significant promise for advanced multifunctional optoelectronic device applications.