Optoelectronic Applications Research Articles

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.

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.

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.

Strategic Design of Anion-Responsive Triarylboranes Exhibiting Colorimetric and Fluorometric Red-Shift for Sensing and Optoelectronic Applications.

Triarylboranes (TABs) have been employed as colorimetric and/or fluorometric anion sensors. The majority of TAB-based anion sensors exhibit blue-shift modes of absorption and photoluminescence (PL) or turn off of PL, attributed to the intrinsic electronic polarity of the trivalent boron unit in their molecular designs. In this Concept article, we introduce a novel approach to modulating the photophysical properties of TABs toward a red-shift mode by balancing the dual, opposing roles of the amine-bridged TAB (phenazaborine). This molecular design strategy enables significant changes in color and emission response to anions, shifting to the lower energy regime in solution. Additionally, this approach is applicable to the solid-state modulation of PL in films and organic light-emitting diodes (OLEDs).

Broadband Light Harvesting from Scalable Two-Dimensional Semiconductor Multi-Heterostructures.

Broadband absorption in the visible spectrum is essential in optoelectronic applications that involve power conversion such as photovoltaics and photocatalysis. Most ultrathin broadband absorbers use parasitic plasmonic structures that maximize absorption using surface plasmons and/or Fabry-Perot cavities, which limits the weight efficiency of the device. Here, we show the theoretical and experimental realization of an unpatterned/planar semiconductor thin-film absorber based on monolayer transition-metal dichalcogenides. We experimentally demonstrate an average total absorption in the visible range (450-700 nm) of >70% using <4 nm of semiconductor absorbing materials scalable over large areas with vapor phase growth techniques. Our analysis suggests that a power conversion efficiency of 15.54% and a specific power >300 W g-1 may be achieved in a photovoltaic cell based on this metamaterial absorber.

A comparative analysis of optical and electrical properties of pure CuO and Zn doped CuO nanoparticles for optoelectronic device applications

A comparative analysis of optical and electrical properties of pure CuO and Zn doped CuO nanoparticles for optoelectronic device applications

Gan Photonic Crystals: Spectral Dynamics in UV, X‐Ray, and Alpha Radiation

In this work, a comparative analysis of gallium nitride (GaN) thin films is conducted, both with and without photonic crystal (PhC) structures, focusing on their scintillation and photoluminescence properties. GaN's suitability for diverse optoelectronic and radiation detection applications is analyzed, and this study examines how PhC implementation can enhance these properties. Methodologically, the emission spectra is analyzed from 5.9 keV X‐ray sources, decay curves, pulse height spectra in response to 241Am 5.5 MeV alpha‐rays, and photoluminescence spectra induced by UV excitation. The findings demonstrate a substantial increase in quantum efficiency for PhC GaN, nearly tripling the light yield that of conventional plain GaN thin films under the UV excitation. The enhancement is predominantly attributed to the PhC GaN's proficiency in guiding light at 550 nm, a feature indicative of its spectral filtering capabilities, as detailed in the study. Furthermore, side‐band scintillations, stemming from inherent materials like Chromium that generate scintillations at diverse wavelengths, are effectively mitigated. A key finding of this study is the effective detection of light not only at the rear but also along the lateral sides of the films, offering new possibilities for radiation detector design and architecture.

Responsive Chirality: Tailoring Supramolecular Assemblies with External Stimuli as Future Platforms for Electronic/ Spintronic Materials.

Supramolecular chirality is the major branch of supramolecular chemistry, which not only plays important roles in biological processes but also in synthetically designed aggregated systems. To understand the complex processing of biological systems, the only way is to design supramolecular chiral ensembles that mimic natural biomolecules such as Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), amino acids, etc. In addition, chiral systems and self-assemblies as molecular motifs with breaking spatial inversion symmetry have been regarded as key substances in electronics and spintronics as well as in fundamental chemistry and physics. Here, in this review, our major concern is understanding modulation in spatial arrangements and packing modes under the impact of any external stimuli, which results in tailoring the handedness of resulted supramolecular chiral superstructures. We, in this review, highlighted the role of external stimuli such as solvent, chemical additives, photo exposure, etc. in altering the supramolecular chirality for their future utility as "active switches" in optoelectronic and spintronic devices and applications.

Heteroepitaxy of ε‐Ga2O3 thin film for artificial synaptic device

AbstractEmerging‐wide bandgap semiconductor Ga2O3 shows distinct characteristics for optoelectronic applications and a stable crystal phase of Ga2O3 is highly desired. Herein, we have first reported a metal‐semiconductor‐metal structure photonic synaptic device based on the ε‐Ga2O3 thin film. The ε‐Ga2O3 epilayer is grown on the c‐sapphire with a low temperature nucleation layer, which presents a crystal orientation relationship with the c‐sapphire (ε‐Ga2O3 &lt;010&gt; // c‐sapphire &lt;1–100&gt; and ε‐Ga2O3 &lt;001&gt; // c‐sapphire &lt;0001&gt;). The ε‐Ga2O3 photonic device was stimulated by UV pulses at different pulse widths, pulse intervals, and reading voltages. Under the UV pulse excitation, the photonic device exhibits primary synaptic functions including excitatory postsynaptic current, short term memory, pair pulse facilitation, long term memory, and STM‐to‐LTM conversion. In addition, stronger and repeated stimuli can naturally contribute to the higher learning capability, thus prolonging the memory time.

A C3‐symmetric like structurally twisted molecular architecture: mechano/fluorochromic behavior and selective multiphase detection of Pd (II)

Triaminoguanidinium (TG)‐based C3‐symmetric‐like molecular architectures with diverse donors and acceptors are well established as organic molecular materials for promising stimuli‐responsive and metal sensing‐based applications. However, the mechanofluorochromic (MFC) response was unremarkable upon applying external mechanical stress. Even though some show MFC features, there was no optical shift under ambient light. In this paper, we developed a novel C3‐symmetric molecule, TAC3, containing the TG core linked with conformationally twisted thiophene‐linked anthracenyl terminals. Three conformationally deformed hands in TAC3 respond against external mechanical stimuli with a redshifted absorption and emission, easily detectable through the naked eye. Although MFC features were reported before for such C3‐symmetric molecules, the change in absorbance was not identified. In addition, TAC3 could selectively detect Pd2+ through extreme emission quenching (green to black). The mechanochromism and sensing outcomes are elucidated by the experimental and theoretical support. Compared to the previous reports, the notable 2:3 (metal: ligand) binding due to geometric restriction creating a specific pocket size for Pd+2 is unusual for this system. The onsite application on Pd2+ detection and measurable MFC features are demonstrated to validate the potential of this C3‐symmetric molecule in advanced optoelectronic applications such as security writing and Pd2+ ion detection.

Synthesis of Diketopyrrolopyrrole Based Photoactive Materials via Photoredox C−H Activation

AbstractThe synthesis of diketopyrrolopyrrole (DPP) derivatives followed the well‐known conventional cross‐coupling methods such as Suzuki, Stille, Sonogashira, and Negishi cross‐coupling reactions. However, these methods required unfavorable reaction conditions, organometallic precursors, and high temperatures. In addition, the synthesis of conventional cross‐coupling partners including organoboranes, stannane, and acetylenes required drastic reaction conditions and strong bases. In this work, a wide variety of thiophene‐diketopyrrolopyrrole (TDPP)‐based semiconducting materials (36 compounds) were synthesized via Pd‐catalysed photoredox methodology by using N‐hydroxyphthalimide (NHP) based coupling partners, which can be readily prepared from N‐hydroxyphthalimide and carboxylic acid or aldehyde derivatives via single step C−O bond formation reactions with good yield (80–90 %). This methodology minimizes additional synthetic steps, harsh reaction conditions, and high temperature (100–150 °C). Optoelectronic studies suggest that the synthesized materials have suitable band gap, HOMO and LUMO levels for variety of optoelectronic applications. To the best of our knowledge, this is the first report on the synthesis of TDPP‐based π‐conjugated materials via the photoredox method.

Flexible Asymmetrically Transparent Conductive Metamaterial Electrode Based on Photonic Nanojet Arrays

AbstractFlexible transparent electrodes, encompassing the combination of optical transparency and electrical conductivity, empower numerous optoelectronic applications. While the main efforts nowadays concentrate on developing wire meshes and conductive oxides, those technologies are still in a quest to find a balance between price, performance, and versatility. Here we propose a new platform, encompassing the advantages of nanophotonic design and roll‐to‐roll large‐scale lithography fabrication tools, granting an ultimate balance between optical, electrical, and mechanical properties. The design is based on an array of silica microspheres deposited on a patterned thin aluminum film attached to a flexible polymer matrix. Microspheres are designed to squeeze 80% light through nanoscale apertures with the aid of the photonic nanojet effect given the light impinges the structure from the top. The photonic structure blocks the transmission for the backpropagation direction thus granting the device with the high 5‐fold level of asymmetry. The patterned layer demonstrates a remarkable 2.8 Ω sq−1 sheet resistance comparable to that of a continuous metal layer. The high conductivity is shown to be maintained after a repeatable application of strain on the flexible electrode. Such remarkable optical, mechanical and electrical properties, makes the demonstrated device an essential component for applications, where such attributes are critically required.

Investigation of structural, morphological, optical and photoluminescence features of Mg-doped Zn0.96Ni0.04O nanoparticles for optoelectronics applications

Investigation of structural, morphological, optical and photoluminescence features of Mg-doped Zn0.96Ni0.04O nanoparticles for optoelectronics applications

Magneto-optical properties of heavily Fe-doped GaAs: a density functional approach.

The magneto-optical properties of heavily iron-doped GaAs are investigated. Complex permittivity, optical conductivity and absorption coefficients are mainly discussed using spin-polarized electronic band structures close to the Fermi energy level. Furthermore, prominent magneto-optical properties in visible light and ultraviolet regions, including magnetic circular dichroism as well as complex Kerr and Faraday rotation angles, are presented and discussed. A density functional approach corroborated by some experimental results indicates that GaAs with 25% Fe dopants either in As or Ga sites is a promising ferromagnetic material and a useful platform for optoelectronic and spintronic device applications.

Buckybowl-Based Fullerene Receptors.

Buckybowls, bowl-shaped polyaromatic hydrocarbons, have received intensive interest owing to their multifaceted potentials in supramolecular chemistry and materials science. Buckybowls possess unique chemical and physical properties associated with their concave and convex faces. In view of the shape complementarity, which is one of the key factors for host-guest assembly, buckybowls are ideal receptors for fullerenes. In fact, the host-guest assembly between buckybowls and fullerenes is one of the most active topics in buckybowls chemistry, and the resulting supramolecular materials show promising applications in optoelectronics, biomaterials, and so forth. In this tutorial review, we present an overview for the progress on fullerene receptors based on buckybowls over the last decade.

Quasi-bound state in the continuum enhancing background limited infrared detectivity

Quasi-bound states in the continuum (quasi-BIC) have tunable high Q factors and thus have many potential applications in optoelectronics. Here, we propose to construct a quasi-BIC with a perturbated elliptical-cylinder photonic crystal slab, and then develop a new way based on the quasi-BIC to address the background noise problem of infrared detectors. By integrating the photonic crystal slab with a quantum well infrared photodetector (QWIP), and by pushing the quasi-BIC system with absorption to the critical coupling state, an ultra-narrow photoresponse band (Q factor equal to 1150) with a high peak quantum efficiency (over 60%) is achieved in the long-wavelength infrared range. The critical coupling state is realized by matching the radiation Q factor, which is mainly controlled by the quasi-BIC, to the absorption Q factor, which is mainly controlled by the doping of the quantum wells (QWs). This device rejects most background radiation and thus significantly suppresses the background noise, resulting in a background limited specific detectivity (DBLIP∗) 11.85 times that of a conventional ideal photoconductor. A detailed formula is employed for calculation of DBLIP∗, incorporating the wavelength and incident angle dependence of the quantum efficiency. The ultra-narrow photoresponse band with a high peak responsivity can be tuned over the photosensitive wavelength range of the QWs by simply modifying the in-plane structural parameters. This work opens a new avenue to greatly enhance the specific detectivity for infrared detectors based on the joint effect of quasi-BIC and critical coupling.

Spin-Lifetime Probe for Detecting Intramolecular Noncovalent Interaction in Organic Semiconductors.

Intramolecular noncovalent interaction (INCI), a crucial strategy for effectively enhancing molecular planarity and extending π-electron delocalization in organic semiconductors (OSCs), has played an increasingly important role in optoelectronic applications. However, though the INCI formation is regularly considered to improve the device performance by literature, there is no feasible approach to directly and reliably characterizing its formation in practical-OSC films thus far. Here in this study, by theoretical analysis and calculation, the generation of INCIs in OSCs is found, normally consisting of relatively heavy elements, such as O···Se, O···S, N···S interactions, etc., can induce enhanced strength of spin-orbit coupling, the primary factor dominating spin lifetime in OSCs. Based on this newly discovered theory, spin lifetime is creatively employed as a probe for sensitively detecting INCIs in OSC films via spin valves or field-induced electron paramagnetic resonance, respectively. This study will highly promote academic and applicable developments of the cross-cutting frontier research field between organic spintronics and electronics.

Effects of Pt doping on surface properties and quenching of band edge emission in ZnO

Pt doped ZnO thin films were synthesized on soda-lime glass substrates using a cost-effective sol-gel method, followed by spin coating and thermal annealing at various temperatures. Several characterization techniques such as UV–Vis absorption spectroscopy, photoluminescence (PL), field emission scanning electron microscopy (FESEM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) are exploited to investigate the Pt doping effects on surface and optical properties of ZnO thin films. UV–Vis analysis demonstrated a slight decrease in the optical band gap from 3.3 eV to 3.2 eV with increased annealing, indicating enhanced suitability for optoelectronic applications. FESEM imaging revealed distinct worm-like structures and small Pt metal nanoparticles in unannealed samples, while thermal treatment supported the formation of spherical Pt nanoparticles and improved conductive pathways in the films. The Wagner diagram, coupled with Auger line transitions from XPS, quantified the oxidation states and chemical environments of Zn and Pt, respectively. Notably, the observed changes in the binding energy of the Zn-2p junction and the kinetic energy of the Zn-LMM Auger junction were significantly influenced by the Pt doping and the electronic properties of the substrate. The Wagner diagram provided a comprehensive visual representation of the parameters, facilitating a deeper understanding of electronic interactions and structural dynamics at the atomic level. XPS results confirmed the presence of ZnO, Zn(OH)2, Pt0 and PtO2 phases, indicating stability and constutient's interactions. ToF-SIMS also validated the uniform distribution of Pt nanoparticles within the ZnO thin film, confirming the effectiveness of the sol-gel method. As a result of Pt doping, PL studies revealed a large quenching effect on band edge emission in the UV and visible emission region of ZnO thin film, which is due to Pt acting as a recombination center for photogenerated carriers. Overall, our results highlight the influence of annealing and Pt incorporation on the optical and structural properties of ZnO thin films and highlight their potential applications for photonics and catalysis.

Theoretical aspects of structure, electronic, optical and elastic properties of Ca(1-x)CxSe mixed alloys in binary and ternary phases

The structural, optoelectronic, and elastic properties of Carbon doped Calcium Selenide binary and ternary semiconductor alloys with the general form of Ca(1-x)CxSe, 0 ≤ x ≤ 1 in B1 and B3 phases have been scrutinized adopting augmented plane wave plus local orbital methods within density functional theory applying different approximations like the Local density approximation (LDA), Wu-Cohen-Generalized Gradients Approximation (WC-GGA) and modified Becke-Johnson (mBJ). Structural properties summarize the crystal structure, relevant atomic positions, lattice constant, Bulk modulus B0, minimum energy E0, and minimum volume V0. Elastic constants confirm the structure stability of the B1 and B3 phases. The band gap was modified from a wider for appropriate optoelectronic devices application to narrow that enhanced the range of applicability of these binary and ternary semiconductor compounds for optoelectronic device applications. Whereas optical properties which include the study of zero frequency limit of static dielectric constant ε0(ω) with its real and imaginary parts, static refractive index n(0), optical reflectivity R(ω), optical absorption coefficient α(ω), optical conductivity σ(ω), and loss function L(ω) studied comprehensively to get real electrical and optical properties of these materials and give semiconductor market best alternative candidate which shows its effectiveness in the visible, ultraviolet and infrared region of the electromagnetic spectrum. Obtained results compared together and with the available experimental along with theoretical work on these binary and ternary Carbon-doped Alkaline earth Selenide.

Characterization and Performance Evaluation of Ni-Doped SnO2 Thin Films for Optoelectronic Applications: Structural, Optical, and Electrical Insights

Abstract Undoped and Ni-doped tin oxide thin films were synthesized using the spray pyrolysis technique on ordinary glass substrates. The study aimed to investigate the physico-chemical properties of these thin films using various characterization techniques. X-ray diffraction analysis revealed a polycrystalline behavior with a tetragonal structure and a preferential orientation along the direction for both undoped and Ni-doped SnO2 films. Raman spectroscopy confirm the tetragonal rutile structure and shows a slight enhancement of crystallinity for 4% Ni doped SnO2 thin films. Optical measurements showed a decrease in transmittance with increasing dopant ratio, indicating reduced transparency, and a decrease in band gap with Ni insertion. Electrical measurements, conducted through I-V curve analysis, confirmed Ohm's law compliance and indicated a decrease in resistivity with Ni doping, suggesting improved electrical conductivity. Additionally, the study explored the performance of thin-film solar cells utilizing SnO2 as a transparent conducting layer through numerical simulations using SCAPS-1D software. The effects of Ni doping on the solar cell performance were examined, suggesting potential enhancements or modifications in efficiency and functionality. Overall, the findings provide valuable insights into the structural, optical, and electrical properties of undoped and Ni-doped SnO2 thin films, offering promising avenues for their application in optoelectronic devices.