Applications In Optoelectronic Devices Research Articles

Synthesis of Thionated Perylenediimides: State of the Art and First Investigations of an Alternative to Lawesson's Reagent.

Perylenediimides (PDIs) are composed of a central perylene ring, on which are grafted two imide groups at the peri positions. Thionated PDIs are characterized by the substitution of one or more oxygen atoms of these imide functions with sulfur atoms. This structural modification alters the electronic properties with a redshift of the optical absorption accompanied by modification of the charge transport characteristics compared to their non-thionated counterparts. These properties make them suitable candidates for applications in optoelectronic devices, such as organic light-emitting diodes and organic photovoltaics. Moreover, the presence of sulfur atom(s) can favor the promotion of reactive oxygen species production for photodynamic and photothermal therapies. These thionated PDIs can be synthesized through the post-functionalization of PDIs by using a sulfurizing reagent. Nevertheless, the main drawbacks remain the difficulties in adjusting the degree of thionation and obtaining tri- and tetrathionated PDIs. Up to now, this thionation reaction has been described almost exclusively using Lawesson's reagent. In the current study, we present our first investigations into an alternative reagent to enhance selectivity and achieve a greater degree of thionation. The association of phosphorus pentasulfide with hexamethyldisiloxane (Curphey's reagent) clearly demonstrated higher reactivity compared with Lawesson's reagent to attain multi-thionated PDIs.

Transition metal ion doped Mg-Zn manganites for optoelectronic device applications

This work aimed at synthesizing Mg0.5Zn0.5Mn1.95(Fe/Co/Ni)0.05O4 nanoparticles using sol–gel auto-combustion method. Structural studies (XRD, Rietveld, Raman) confirmed the tetragonal spinel structure with I41/amd space group and average crystallite size ranged between 18–22.8 nm. The morphologies and compositions of these nanoparticles were studied using SEM and EDX. UV–Vis spectra demonstrated significant enhancement in the absorbance values. The estimated optical band gaps vary between 1.6 to 1.77 eV. Frequency-dependent dielectric and impedance spectroscopic studies (at room temperature) reveal exciting results. Thus, tailoring of dielectric properties and optical band gaps of these transition metals doped Mg-Zn manganite nanoparticles may find potential applications in optoelectronics devices.

Nonlinear Optical Saturable Absorption Properties of 2D VP Nanosheets and Application as SA in a Passively Q-Switched Nd:YVO4 Laser.

Two-dimensional (2D) violet phosphorus (VP) plays a significant role in the applications of photonic and optoelectronic devices due to its unique optical and electrical properties. The ultrafast carrier dynamics and nonlinear optical absorption properties were systematically investigated here. The intra- and inter-band ultrafast relaxation times of 2D VP nanosheets were measured to be ~6.83 ps and ~62.91 ps using the pump-probe method with a probe laser operating at 1.03 μm. The nonlinear absorption coefficient βeff, the saturation intensity Is, the modulation depth ΔR, and the nonsaturable loss were determined to be -2.18 × 104 cm/MW, 329 kW/cm2, 6.3%, and 9.8%, respectively, by using the Z-scan and I-scan methods, indicating the tremendous saturable absorption property of 2D VP nanosheets. Furthermore, the passively Q-switched Nd:YVO4 laser was realized with the 2D VP nanosheet-based SA, in which the average output power of 700 mW and the pulse duration of 478 ns were obtained. These results effectively reveal the nonlinear optical absorption characteristics of VP nanosheets, demonstrating their outstanding light-manipulating capabilities and providing a basis for the applications of ultrafast optical devices. Our results verify the excellent saturable absorption properties of 2D VP, paving the way for its applications in pulsed laser generation.

Experimental and DFT investigations of Al-doped ZnO nanostructured thin films

Al doped ZnO thin films at different concentrations have been successfully synthesized, characterized experimentally, and investigated theoretically by density functional theory (DFT). The crystal structure analysis was carried out using X-ray diffraction (XRD) data. Wurtzite structures of a single phase with a preferred orientation along the (002) plane are obtained. The surface morphology has been investigated by atomic force microscopy (AFM) which showed homogeneous and compact surfaces with spherical shape grains that change to a wave like nematic structure with increasing Al doping rate. For a complete characterization, experimental and theoretical analysis of optical and electrical properties have been done using UV–Vis spectrophotometry, the four-probe method, electronic band structure and density of states calculations, and the Boltz-Trap code based on the semi classical theory of Boltzmann. Both, experimental and theoretical, studies indicate an increase in gap energy with high transparency in the visible region and electrical conductivity improvement due to a non-localized state around the Fermi level. The experimental and theoretical studies agree well and show a similar tendency of the results. Therefore, these properties of Al-doped ZnO open a new avenue for optoelectronic and photonic device applications.

Unveiling excitons in two-dimensional -pnictogens.

In this paper, we investigate the optical, electronic, vibrational, and excitonic properties of four two-dimensional -pnictogen materials-nitrogenene, phosphorene, arsenene, and antimonene-via density functional theory calculations and the Bethe-Salpeter equation. These materials possess indirect gaps with significant exciton binding energies, demonstrating isotropic behavior under circular light polarization and anisotropic behavior under linear polarization by absorbing light within the visible solar spectrum (except for nitrogenene). Furthermore, we observed that Raman frequencies red-shift in heavier pnictogen atoms aligning with experimental observations; simultaneously, quasi-particle effects notably influence the linear optical response intensively. These monolayers' excitonic effects lead to optical band gaps optimized for solar energy harvesting, positioning them as promising candidates for advanced optoelectronic device applications.

Effect of cadmium concentration on the structural, morphological, and optical properties of ZnS nanoparticles

The present study is focused on the synthesis and characterization of the Zn1−xCuxS nanoparticles at x = 0, 0.03, 0.05, 0.07 that find application in optoelectronic devices. The synthesized nanoparticles were subjected to various characterizations. From the XRD profile, it was found that Zn1−xCuxS nanoparticles are in a cubic structure. The EDAX spectrum confirms that zinc, sulfur, and cadmium are present in stoichiometric ratios. The FE-SEM and TEM nanographs confirm the formation of spherical-shaped clusters. The crystal structure and texture of the samples were confirmed by SAED patterns. The specific surface area and pore diameter were estimated using a BET surface analyzer. The band gap of the samples was determined using Tauc’s and Cody’s relation, and it decreased as the Cd concentration increased. The Zn1−xCuxS nanoparticles exhibited photoluminescence, and emission peaks were observed in the visible region. The XPS studies confirmed the presence of dopant cadmium in the Cd2+ ions state.

Orientation-Dependent Photoconductivity of Quasi-2D Nanocrystal Self-Assemblies: Face-Down, Edge-Up Versus Randomly Oriented Quantum Wells.

Here, strongly orientation-dependent lateral photoconductivity of a CdSe monolayer colloidal quantum wells (CQWs) possessing short-chain ligands is reported. A controlled liquid-air self-assembly technique is utilized to deliberately engineer the alignments of CQWs into either face-down (FO) or edge-up (EO) orientation on the substrate as opposed to randomly oriented (RO) CQWs prepared by spin-coating. Adapting planar configuration metal-semiconductor-metal (MSM) photodetectors, it is found that lateral conductivity spans ≈2 orders of magnitude depending on the orientation of CQWs in the film in the case of utilizing short ligands. The long native ligands of oleic acid (OA) are exchanged with short-chain ligands of 2-ethylhexane-1-thiol (EHT) to reduce the inter-platelet distance, which significantly improved the photoresponsivity from 4.16, 0.58, and 4.79mAW-1 to 528.7, 6.17, and 94.2mAW-1, for the MSM devices prepared with RO, FO, and EO, before and after ligands exchange, respectively. Such CQW orientation control profoundly impacts the photodetector performance also in terms of the detection speed (0.061 s/0.074 s for the FO, 0.048 s/0.060 s for the EO compared to 0.10 s/0.16 s for the RO, for the rise and decay time constants, respectively) and the detectivity (1.7×1010, 2.3×1011, and 7.5×1011 Jones for the FO, EO, and RO devices, respectively) which can be further tailored for the desired optoelectronic device applications. Attributed to charge transportation in colloidal films being proportional to the number of hopping steps, these findings indicate that the solution-processed orientation of CQWs provides the ability to tune the photoconductivity of CQWs with short ligands as another degree of freedom to exploit and engineer their absorptive devices.

Exploring the Post-Annealing Influence on Stannous Oxide Thin Films via Chemical Bath Deposition Technique: Unveiling Structural, Optical, and Electrical Dynamics

Stannous oxide (SnO2) thin films have garnered significant attention for their promising applications in various electronic and optoelectronic devices. In this study, we investigate the impact of post-annealing on the structural, optical, and electrical properties of stannous oxide thin films deposited using the chemical bath deposition (CBD) technique. The thin films were prepared on a Borosilicate glass substrate, followed by a controlled annealing process to enhance their performance. Structural analysis was conducted using techniques such as X-ray diffraction (XRD) to examine the cubic crystalline structure and the crystallite size increase induced by post-annealing. The results revealed alterations in grain size from the SEM and the purity of samples confirmed from EDX results. The optical properties of the Stannous oxide thin films were examined using UV-Vis spectroscopy. The optical absorption and bandgap characteristics were analyzed to understand how post-annealing influences the optical behavior of the thin films. Where the optical absorption was 320nm and the bandgap ranges were 3.86eV to 3.83eV. Furthermore, the electrical properties of the thin films were evaluated semiconducting nature, and conductivity increased with rising post-annealing. The findings from this study contribute to the understanding of the role of post-annealing in tailoring the properties of Stannous oxide thin films. The optimization of structural, optical, and electrical characteristics is crucial for their successful integration into electronic and optoelectronic devices.

Structural, electronic, magnetic and thermodynamic properties of ZrCoTiX (X = Ga and Sn) alloys

Structural, electronic, magnetic, elastic, thermodynamic and optical properties of ZrCoTiX (X = Ga and Sn) alloys have been investigated using density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method. Half-metallic nature of ZrCoTiGa1-ySny (y = 0, 0.25, 0.5, 0.75 and 1) alloys is predicted which justifies their applicability in spintronic devices and the respective magnetic moments are obtained as 1.99, 2.25, 2.51, 2.76 and 3.02 μB/f. u. in accordance with the Slater-Pauling rule. Elastic parameters validated the mechanical and thermodynamic stabilities of these alloys. The Curie temperature (TC) is determined using mean field approximation theory as 516.04 and 941.17 K for ZrCoTiGa and ZrCoTiSn, respectively. The optical properties of these alloys demonstrated their applicability in optoelectronic devices. Moreover, the temperature dependent thermodynamic properties like entropy, heat capacity, thermal expansion, etc. are reported for ZrCoTiGa and ZrCoTiSn in the pressure range 0-40 GPa.

Study on the effects of VO and Hi on the absorption spectrum and conductivity of Ti doped β-Ga2O3

β-Ga2O3 has many excellent properties, but poor electrical conductivity limits its application in optoelectronic devices. At present, some progress has been made in the study of Ti doping on the photoelectric properties of β-Ga2O3. However, few studies on the effects of Ti doping and VO-Hi co-existence on photoelectric properties of β-Ga2O3. Defects (VO) and unintentional impurities (Hi) will inevitably exist during the preparation of β-Ga2O3. Given these problems, the effects of Ti doping and VO-Hi co-existence on photoelectric properties of β-Ga2O3 were studied using first-principles GGA+U method. The electronic structure, dielectric function, absorption spectrum, effective mass, mobility, and conductivity of the system were calculated and analyzed. The results indicate that with the increase of Ti doping concentration, the bandgap of the Ti doped β-Ga2O3 system gradually narrows. Ti doping causes a red shift in the peak of the absorption spectrum and effectively improves the conductivity of the system. The O vacancy reduces the conductivity of the system, while the interstitial H increases the conductivity of the system. Thus, Ti-doped β-Ga2O3 material is helpful for preparing new optoelectronic devices.

Remarkable Optoelectronic Characteristics of Synthesizable Square‐Octagon Haeckelite Structures: Machine Learning Materials Discovery

AbstractThe research explores new compounds with structures similar to square‐octagonal beryllium oxide, commonly known as Haeckelites. The goal is to identify semiconducting variations compounds that can be synthesized and show promising potential in optoelectronic devices. Start with 1083 binary Haeckelite structures, and to test the synthesis potential of these materials quickly, develop new descriptors and use machine learning techniques. As a result, it identifies a subset of 350 materials with suitable properties in terms of phase stability and electronic perspective. These materials are further investigated to analyze their electronic structure and phase stability, which are determined through density functional theory calculations. The phase stabilities of the predicted semiconducting Haeckelites are also compared to other binary compounds using an evolutionary structure search algorithm. The comprehensive methodology also includes examining the dynamic stabilities through phonon calculations and mechanical properties through elastic constant calculations. Eventually, 13 new Haeckelite compounds are discovered, demonstrating exceptional stability and performance in electronic tests. Among these compounds, eight have shown remarkable absorption coefficients and are considered promising candidates with high reflectivity. Additionally, they have exhibited high electron mobility. These findings strongly suggest the potential of these compounds for synthesis and their application in optoelectronic devices.

Probing optoelectronic and thermoelectric properties of double perovskite halides Li2CuInY6 (Y = Cl, Br, I) for energy conversion applications

Recently, double perovskite halides (DPHs) become crucial due to their potential applications in optoelectronic devices due to their stability, non-toxicity, superior oxidation resistance, high conversion efficiency, and high temperature stability. In the current study, we explored DPHs Li2CuInY6 (Y = Cl, Br, I) employing Wien2k package to analyze the structural stability, optoelectronic and thermoelectric features. The formation energy and Born stability criteria are computed to confirm thermodynamic and structural stability. Studied DPHs have direct bandgaps nature investigated by modified Becke and Johnson (mBJ) potential. Calculated values of bandgap decreases, when replace halide ion from Cl to I, indicate tuning from visible to infrared (IR) region of electromagnetic spectrum. Their band edge tuning across the visible to infrared border is reliant on replacement, which makes them suitable for projects involving opto-electronic devices. Further, optical features are investigated in terms of incident photon energy in order to assess the optical output. Lastly, electronic thermoelectric performance is computed using the figure of merit (ZT) for all DPs. Computed results of direct bandgap and optical behavior show that DP Li2CuInCl6 can be used as photovoltaic devices as compared to DPs Li2CuInBr6 and Li2CuInI6.

Polyvinylalcohol Composite Filled with Carbon Dots Produced by Laser Ablation in Liquids.

Carbon dots (CDs), owing to their excellent photoluminescent features, have been extensively studied for physics preparation methods and for biomedical and optoelectronic device applications. The assessment of the applicability of CDs in the production of luminescent polymeric composites used in LEDs, displays, sensors, and wearable devices is being pursued. The present study reports on an original, environmentally friendly, and low-cost route for the production of carbon dots with an average size of 4 nm by laser ablation in liquid. Jointly, to prove the significance of the study for a wide range of applications, a free-standing flexible polyvinyl alcohol (PVA) composite containing photoluminescent carbon dots was manufactured. CDs were prepared using targets of porose charcoal with a density of 0.271 g/cm3 placed in phosphate-buffered saline (PBS) liquid solution and irradiated for 30 min by pulsed IR diode laser. The optical properties of the obtained suspension containing carbon dots were studied with UV-ViS and FTIR spectroscopies. The photoluminescence of the produced carbon dots was confirmed by the emission peak at 480 nm in the luminescence spectrum. A narrow luminescence band with a full width at half-maximum (FWHM) of less than 40 nm could be an asset in spectral emission analysis in different applications. Atomic force microscopy confirms the feasibility of manufacturing CDs in clean and biocompatible environments, paving the way for an easier and faster production route, crucial for their wider applicability.

Anthocyanins of Delonix Regia Floral Petals: A Novel Approach on Fluorescence Enhancement, Forster Resonance Energy Transfer Mechanism and Photostability Studies for Optoelectronic Applications.

In this work, we focused on extracting the anthocyanin dye in acetone, butanol, ethanol, and water solvents from Delonix regia flowers by a simple maceration extraction process. The identification of functional group analysis, vibrational studies, energy transfer mechanisms, optoelectronic properties, photostability studies, FRET-assisted potential light emissions and photometric properties of the anthocyanin dyes are successively investigated. FTIR spectroscopy and vibrational studies have confirmed the existence of polyphenolic groups in 2-phenyl chromenylium (anthocyanin) dyes. The optoelectronic results show the least direct bandgap (2.04eV), indirect bandgap (1.55eV), Urbach energy (0.380eV), high refractive index (1.20), dielectric constant (2.794), and high optical conductivity (1.954 × 103 S/m) for the anthocyanin dye extracted found in water solvent. The photoluminescence properties such as Stoke's shift, high quantum yield, and lifetime results show that anthocyanin dyes are promising candidates for red-LEDs and optical materials. The absorption and emission spectra of the anthocyanin dyes follow the mirror image rule and the Franck-Condon factor exists between vibrational energy levels corresponding to all the electronic transitions. The excellent correspondence between the absorption and emission spectra reinforces that the anthocyanins are efficient (46%) FRET probes. Further, photometric properties such as CIE, CRI, CCT and colour purity results of anthocyanins in all studied solvents revealed that this material exhibits orange to red shades (x = 0.48 → 0.54 and y = 0.36 →0.45) and is well suitable for have great potential in the manufacturing of Organic-LEDs and other optoelectronic device applications.

Pressure action on ductility and optoelectronic properties of non-toxic AGeBr[formula omitted] (A = Cs, K, Na, Rb) perovskites

We performed first-principles calculations base on generalized gradient approximation(GGA) in the framework of density functional theory (DFT) to examine the effect of pressure on the structural, mechanical, electronic and optical properties of non-toxic AGeBr3 perovskites (A = Cs, K, Na, Rb) for applications in photovoltaic and optoelectronic devices. The dependence of physical properties is evaluated for several pressure values ranging from 0 GPa to 10 GPa. The determined lattice parameters show agreement with previous values and decrease with the applied pressure. All considered materials show semiconductor behavior with direct bandgap (R ⟶ R) at atmospheric pressure. The hybrid functionals HSE and PBE0 have been used to determine accurate values for bandgaps. A very good agreement was found with available experimental values. The calculated bandgap values were found to be 2.129 [2.608] for CsGeBr3, 2.065 [2.481] for KGeBr3, 2.032 [2.397] for NaGeBr3 and 2.089 [2.530] for RbGeBr3, at the HSE [PBE0] level of theory. However, as the applied pressure increases, a reduction in the bandgap is observed, leading to semiconductor to metallic transition. The materials similarly show improved optical properties under pressure with high absorption coefficients in the visible and ultraviolet regions. In addition, the ductility and stability of the considered materials were found also to improve under hydrostatic pressure, which makes them suitable for incorporation into thin films for high performance optoelectronic devices application.

Monolithically grown CSPbBr3 by chemical vapor deposition for Self-Powered photodetector

The high-quality monolithic growth of perovskite films with larger grains on any substrate is a challenging task due to the instability of morphology, carrier mobility and chemical stability. In this work, we demonstrated the strategy to grow CsPbBr3 films with micron-sized grains along the (002) surface by chemical vapor deposition. The structural and optical characterizations have shown that the as-grown CsPbBr3 thin films are compact and packed without pin holes and have excellent optical quality for use in high-performance optoelectronic devices. The planar photodetector with the device configuration Ag/CsPbBr3/Ag shows a high photoresponsivity of 506.32 A/W and a specific detectivity of 8.29 × 1012 Jones at an incident light illumination of 22.3 µW/cm2. On the other hand, the vertically stacked device with ITO/SnO2/CsPbBr3/CuSCN/Ag configuration exhibits a photoresponsivity of 10.13 A/W at 0.05 V bias and 96 mA/W under 0 V bias. Specifically, the response time of the device in planar geometry is 241/205 ms, while the vertically stacked device has a response time of 20.51/21 ms at 0.05 V bias and 20.51/30 ms at 0 V bias. The results provide a new strategy for the growth of high-quality perovskite thin films and their effective application for high-performance optoelectronic devices.

Fundamentals and emerging optical applications of hexagonal boron nitride: a tutorial

Hexagonal boron nitride (hBN), also known as white graphite, is a transparent layered crystal with a wide bandgap. Its crystal structure resembles graphite, featuring layers composed of honeycomb lattices held together through van der Waals forces. The layered crystal structure of hBN facilitates exfoliation into thinner flakes and makes it highly anisotropic in in-plane and out-of-plane directions. Unlike graphite, hBN is both insulating and transparent, making it an ideal material for isolating devices from the environment and acting as a waveguide. As a result, hBN has found extensive applications in optical devices, electronic devices, and quantum photonic devices. This comprehensive tutorial aims to provide readers with a thorough understanding of hBN, covering its synthesis, lattice and spectroscopic characterization, and various applications in optoelectronic and quantum photonic devices. This tutorial is designed for both readers without prior experience in hBN and those with expertise in specific fields seeking to understand its relevance and connections to others.

Enhanced environmental stability and luminescence performance of CsPbI3 nanocrystals through SDS passivation and LEuH anchoring

CsPbI3 perovskite nanocrystals (NCs) have been identified as promising candidates for optoelectronic devices due to their low bandgap, wide absorption spectrum, and high color purity. However, their practical applications are limited by their vulnerability to transforming into the yellow non-perovskite phase in ambient conditions. In this study, we propose a novel approach to prepare highly stable black-phase CsPbI3 NCs by passivating them with sodium dodecyl sulfate (SDS) and anchoring them with flower-like layered europium hydroxide (LEuH). The addition of SDS to CsPbI3 NCs plays a crucial role in inhibiting defect formation by preventing the ligand from desorbing. Furthermore, LEuH, with its surface OH– groups, effectively anchors the CsPbI3 NCs onto its nanosheets, preventing their agglomeration. The resulting composite LEuH-SDS-CsPbI3 nanocomposites exhibit extraordinary environmental stability, maintaining their phase structure even after 60 days of storage under ambient conditions. Additionally, their photoluminescence quantum yield reaches an impressive 95 %. The exceptional luminescence performance of the LEuH-SDS-CsPbI3 nanocomposites opens up new possibilities for their application in optoelectronic devices. Furthermore, when used in white LEDs, these nanocomposites exhibit excellent luminescence efficiencies, further highlighting their potential for commercial utilization in the field.

Impact of annealing on Cu2O doped with Na/Co: Structural, optical, and electrochemical consequences

Impact of annealing on Cu2O doped with Na/Co: Structural, optical, and electrochemical consequences

High-performance of low temperature solution-processed P-channel CuGaO thin film transistors

The exploration of p-type metal-oxide semiconductors (MOS) has garnered growing interest, particularly for their potential applications in next-generation optoelectronic devices, display backplanes, and low-power consumption complementary MOS (CMOS) circuits. Here, we introduced low-temperature solution-processed copper gallium oxide (CuGaO) films for p-channel thin-film transistors (TFTs). Hall Effect measurements confirmed the p-type conduction of CuGaO, revealing a conductivity and mobility of 3.76 ×10−2 S/cm and 7.89 cm2V–1s–1, respectively. The p-channel CuGaO-250 TFT demonstrated a field-effect mobility (μFE) of 1.24 cm2V–1s–1, the lowest subthreshold swing (SS) of 519 mV/dec, and an ON/OFF current ratio (ION/IOFF) of ∼104 at a low operating voltage. The notable improvement in TFT performance can be attributed to the quality of the CuGaO-250 film, a smooth surface morphology, and a reduction of interfacial traps between the semiconductor and the gate insulator. Hence, low-temperature fabrication of the p-channel CuGaO TFT holds promise for implementing metal oxide-based TFT and complementary metal oxide semiconductor (CMOS) circuits in next-generation displays.