Optoelectronic Characteristics Research Articles

Lead-Free Double Perovskites Rb2TlSbX6 (X=Cl, Br, and I) As an Emerging Aspirant for Solar Cells and Green Energy Applications

This study utilized the WIEN2k simulation program to examine the structural, mechanical, thermodynamic, optoelectronic, and thermoelectric characteristics of lead-free double perovskites Rb2TlSbX6 (X=Cl, Br, and I). The objective is to assess their potential contribution to next-generation photovoltaic and thermoelectric systems. The ab initio molecular dynamics (AIMD) has validated that materials are thermodynamically stable. Examining mechanical features confirms the mechanical stability and ductile characteristics of studied perovskites. Rb2TlSbCl6 exhibits superior flexibility and stiffness, whereas Rb2TlSbI6 demonstrates the highest level of anisotropy. The thermodynamic parameters confirm the thermal stability and stronger bonding at elevated pressure and temperature. The electronic features, determined by implementing the GGA-PBE and TB-mBJ functionals, indicate direct band gaps at the Γ- Γ position. The band gap ranges from 1.22 eV to 1.74 eV, 0.94 to 1.34 eV, and 0.81 eV to 1.15 eV for Rb2TlSbCl6, Rb2TlSbBr6, and Rb2TlSbI6, respectively. The analyzed optical characteristics reveal significant absorption and conductivity with decreased reflectance and optical loss between 0 and 6 eV. Rb2TlSbI6 has the greatest dielectric constant, which suggests a lower recombination rate of electron-hole pairs. The thermoelectric characteristics demonstrate a large figure of merit values of 0.78, 0.80, and 0.84 at room temperature. Therefore, these materials have the significant capability forsolar cell technology and may effectively convert thermal energy into usable electrical power.

Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO2 contact deposition temperature

Carrier selective contacts are a primary requirement for fabricating silicon heterojunction solar cells (SHSCs). TiO2 is a prominent carrier selective contact in SHSCs owing to its excellent optoelectronic features such as suitable band offset, work function, and cost-effectiveness. Herein, we fabricated simple SHSCs in an Al/TiO2/p-Si/Ti/Au device configuration. Ultrathin 3 nm TiO2 layers were deposited onto a p-type silicon substrate using the atomic layer deposition method. The deposition temperature of TiO2 layers varied from 100 °C to 250 °C. X-ray photoelectron spectroscopic studies suggest that deposition temperature highly affects the chemical states of TiO2 and reduces the formation of defective state densities at the Fermi energy. The optical band gap values of TiO2 layers are also altered from 3.13 eV to 3.27 eV when the deposition temperature increases. The work function tuning from −5.13 eV to −4.83 eV has also been observed in TiO2 layers, suggesting the variation in Fermi level tuning, which arises due to changes in carrier concentrations at higher temperatures. Several device parameters, such as ideality factor, trap density, reverse saturation current density, barrier height, etc, have been quantified to comprehend the effects of deposition temperature on photovoltaic device performance. The results suggest that the deposition temperature significantly influences the charge transport and device performance. At an optimum temperature, a significant reduction in charge carrier recombination and trap state density has been observed, which helps to improve power conversion efficiency.

Liquid phase exfoliation of few-layer borophene with high hole mobility for low-power electronic devices

Borophene, the two-dimensional allotrope of boron, has garnered significant interest in recent years due to its exceptional electronic, mechanical, and optical properties. In this work, an environment-friendly green approach has been utilized to synthesize p-type borophene, which consists of few layers as evidenced by electron and atomic force microscopic images. The Raman analysis indicated that these borophene layers possess β12 and χ3 phases. The photoemission spectra of these samples exhibit single exponential decay with a long lifetime of 7.2 µsec, showcasing its potential as a phosphorescent material in optoelectronics and quantum technologies. The photo-sensing capability of borophene was investigated by fabricating a Si/SiO2/Borophene/Ti/Pt photo-detector, which achieved an external quantum efficiency of 31 %, maximum photo responsivity of 200 mAW−1 and detectivity of 8.7x1011 Jones. Hall effect van der Pauw measurements revealed the p-type conductivity of the borophene film, along with a high hole mobility of 931.44 cm2V-1s−1 and a charge carrier density of 2 x 1012 cm−3, rendering these layers suitable for high-speed and low power electronic devices. This work emphasizes the importance of novel 2D materials like borophene with exceptional optoelectronic characteristics for developing future low-power electronic devices with remarkable performance.

First-Principles study of the electronic Structure, Optical, and thermoelectric properties of novel WSeX (X=S, Te) Chalcogenides: For energy harvesting application

Excellent thermal stability and tunable optoelectronic features are twouniquecharacteristicsof ternary chalcogenides. The first −principles investigations were carried out to look into the intricate interactions between the optical, thermoelectric, and electronicfeatures of novel ternary chalcogenides. The stability of these studied materials was confirmed by the computed formation energy values. There is a strong correlation between the formation energy and the ionicity of W-X bonds, indicating that materials with lower formation energy are connected to a higher number of ionic bonds. The valence band maximum and conduction band minimum of both WSeS and WSeTe materials are located at the Γ-point, which confirms they are direct band gap semiconductors. The heavier element Te is incorporated, making the electronicstructure of WSeTe more complex than that of WSeS. The ε1(ω) was negative at higher photon energy, which is associated with these materials’ response being closer to that of a metallic in the specified energy range. WSeS and WSeTe exhibit peaks in ε2(ω) representing the highest densities of electronic states that can take part in optical transitions. As fewer states become accessible for the high-energy transitions that make these materials ideal for use in optoelectronics and photovoltaics, as confirmed by the n(ω) decreases as a result of a drop in absorption. The behavior of charge carriers and their interactions with the lattices leads to an almost linear increase in electrical thermal conductivity with temperature. Because electron–phonon scattering, the main type of scattering, increases with temperature, electrical conductivity in these materials often decreases as temperature rises.

Investigation of Opto-Electronic and Thermoelectric Characteristics of Halide Perovskite CdLiCl3 for Energy Conversion Applications at Different Pressure

Investigation of Opto-Electronic and Thermoelectric Characteristics of Halide Perovskite CdLiCl3 for Energy Conversion Applications at Different Pressure

Thermodynamical stability and optoelectronic characteristics of Sr1-xCoxTe: A DFT study

Herein, the structural, electronic, magnetic and optical features of Sr1-xCoxTe alloys are investigated by using first-principles calculations. Stability of alloys is confirmed by the enthalpy of formation energy. The spin-dependent band structure (BS) and density of states (DOS) elucidate the half-metallic ferromagnetic (HMF) nature. For spin-down channel, Sr1-xCoxTe (x = 6.25 %, 12.5 %, 25 %) alloys have bandgap values of 1.30, 0.79 and 0.41 eV, respectively. The computed total magnetic moment for Sr1-xCoxTe (x = 6.25 %, 12.5 %, 25 %) are 3.00003, 5.99801, and 10.01265 μB, respectively. This robust magnetic ordering is primarily originated due to the incorporation of Co cations, which is further confirmed by spin magnetic density visualizer plots. Moreover, the optical features including dielectric constants, absorption, refraction and reflectivity of studied alloys have been analyzed within energy range 0–10 eV. Upon Co incorporation, the resulting alloys become optically active in the visible region of light. Overall, presented results suggest that Co-doped SrTe could be a potential material for optoelectronic and spintronic applications.

Thermally induced Modulation of optoelectronic characteristics In (ZrO2)0.8 doped (CuO) 0.2 screen printed thick films: An Innovative approach to enhanced materials

The Zirconium Dioxide (ZrO2) dopedCopper Oxide (CuO) thick films were fabricated on a glass substrate using the screen printing method, employing sintering temperatures of 500 °C, 550 °C, and 600 °C. The structural characteristics of the doped films were analyzed through Scanning Electron Microscopy (SEM), X-Ray Powder Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the optical properties were assessed via UV–Vis spectroscopy and Photoluminescence (PL) spectroscopy. SEM investigations revealed an increase in nanoparticle grain size and agglomeration as the sintering temperature was raised. XRD results exhibited the polycrystalline nature of the films and an augmented intensity of the monoclinic phase of ZrO2, with a noticeable preferred orientation along the (111) plane, which increased with higher sintering temperatures. FTIR analysis demonstrated slight peak shifts and increased sharpness as the sintering temperature was elevated. UV–Vis spectroscopy indicated a redshift in the reflectance edge, with the band gap transitioning from 3.81 eV (at 500 °C) to 3.65 eV (at 600 °C). These findings were corroborated by PL spectroscopy, which exhibited a redshift in the band emission as the sintering temperature increased. Electrical conductivity displayed semiconducting behavior of the sample. These investigations collectively indicate that elevating the sintering temperature leads to enhanced crystallinity in the films and a reduction in lattice deformations within the composite materials which is crucial for applications in large-area and flexible electronics.

DFT study of structural, elastic and optoelectronic characteristics of novel Rb2CaSnX6 (X = Cl, I) double halide perovskites for optoelectronic applications

DFT study of structural, elastic and optoelectronic characteristics of novel Rb2CaSnX6 (X = Cl, I) double halide perovskites for optoelectronic applications

From Chalcogen Bonding to S-π Interactions in Hybrid Perovskite Photovoltaics.

The stability of hybrid organic-inorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of low-dimensional (LD) perovskites, which incorporate hydrophobic organic moieties, provides an effective strategy to improve their stability, yet often at the expense of their performance. To address this limitation, supramolecular engineering of noncovalent interactions between organic and inorganic components has shown potential by relying on hydrogen bonding and conventional van der Waals interactions. Here, the capacity to access novel LDperovskite structures that uniquely assemble through unorthodox S-mediated interactions is explored by incorporating benzothiadiazole-based moieties. The formation of S-mediated LD structures is demonstrated, including one-dimensional (1D) and layered two-dimensional (2D) perovskite phases assembled via chalcogen bonding and S-π interactions. This involved a combination of techniques, such as single crystal and thin film X-ray diffraction, as well as solid-state NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of S-mediated LD perovskites. The resulting materials are applied in n-i-p and p-i-n perovskite solar cells, demonstrating enhancements in performance and operational stability that reveal a versatile supramolecular strategy in photovoltaics.

Elastic-acoustic, optical and thermoelectric investigation of Cu6AsS5X (X= Br, I) for renewable energy applications

First-principles computations examine the structure, optoelectronic, elastic-acoustic, and thermoelectric characteristics of Cu6AsS5X (X = Br, I). The renowned Perdew – Burke – Ernzerhoff generalized gradient approximation (PBEsol–GGA) was employed to compute the physical and elastic parameters; however, the energy band structure of Cu6AsS5Br and Cu6AsS5I has been more precisely determined by employing the Trans and Blaha technique of the modified Becke-Johnson (TB–mBJ) potential. The lattice constants of Cu6AsS5Br and Cu6AsS5I in the cubic structure increase from 10.24 Å to 10.27 Å as a consequence of an increase in atomic number (ionic size). Several properties are extracted from the computed density of state (DOS) and band structure (BS). The computed values for the gap between the valence and conduction bands indicate that the compounds are semiconducting. These compounds' prominent absorption peaks in the UV energy range suggest that argyrodites can be utilized for optoelectronic (OE) devices operating in this spectral region. The cubic compounds (C11, C12, and C44) elastics constants, as well as different parameters like Kleinman's parameters ζ, Hardness (H), melting temperature (Tm), Lame's constant, Zener anisotropy (A), acoustic behavior and its isotropy, and Poisson ratios (ʋ) are calculated. Furthermore, the thermoelectric properties have been calculated using the BoltzTrap package integrated into WIEN2K. The positive Seebeck coefficient (S), increased electrical conductivity (σ) and low thermal conductivity (k) indicates p-type semiconductors. These compounds' greater Figure of merit (ZT) shows their potential candidacy for thermoelectric applications

Tuning of Optoelectronic Characteristics of Quinoxalineimide-based Novel Non-Fullerene Acceptors for Organic Photovoltaic Applications

Organic solar cells (OSCs) have made remarkable progress due to developing novel materials and device architectures. Herein, we designed six new non-fullerene acceptors (QM1–QM6) having a quinoxalineimide (QI) as the central-building-block. We aimed to explore the potential of QI-containing structures for developing high-performance acceptors for OSCs. These designed molecules possess a fusion of the QI unit with a thienylthiophene backbone and are equipped with various efficient end-capping groups. Extensive theoretical calculations were carried out to evaluate the structural and charge distribution characteristics, including the optical, optoelectronics, density of states, transition density matrix, molecular electrostatic potential (ESP), reorganization energies, and photovoltaic properties. The results revealed that the designed series exhibited improved electron–hole pair coherences, efficient charge transportation, and favorable ESP patterns, suggesting their suitability for enhanced optical and electronic characteristics. Furthermore, the hole and electron overlap analyses demonstrated significant overlap in QM1–QM6, indicating efficient charge transfer and higher charge mobilities. Additionally, the analysis of reorganization energies showed low reorganization energy values, indicating favorable charge mobility rates and potential for high-efficiency solar cell devices. This research establishes a strong foundation for utilizing QI-containing fused units as central building blocks for designing high-performance acceptors, opening up new avenues for advancements in OSCs technology.

Tuning of optoelectronic performance of SrTiO3 by surface termination and thickness

The outstanding optical and electrical properties make ternary oxides highly suitable for advanced optoelectronic applications comparing to the traditional silicon-based materials and heterostructures. SrTiO3 (STO), a pivotal perovskite oxide with a direct energy band gap of 3.2 eV, exhibits significant promise in ultraviolet (UV) photodetection. However, the photovoltaic performance of homoepitaxial STO has long been neglected. In this study, we investigated the optoelectronic characteristics of STO by manipulating the crucial factors of surface termination and thickness using oxide molecular beam epitaxy (oxide MBE). We achieved an exceptional charge carrier mobility of 56.5975 cm2 V-1s−1, along with an impressive ON/OFF ratio of 6000 % and a specific detectivity (D*) of 2.95 × 109 Jones (cm Hz1/2 W−1) under near-UV irradiation at room temperature. We observed a thickness-dependent semiconductor-to-metal transition with a critical thickness of 3.5 u.c. STO. The metallic STO displayed an extremely high mobility exceeding 105 cm2 V−1 s−1, accompanied by a substantial MR value exceeding 1000 % at 3 K. Furthermore, the thickness-dependent Hall effect and photoluminescence (PL) indicated that oxygen defects may govern the semiconducting/metallic behavior of STO. This study illustrates the optoelectrical capabilities of homoepitaxial STO, paving the way for advanced and high-performance photodetection in intricate optical materials and devices through homoepitaxy.

Comparative study of the electronic and optical properties of Rhenium based Chalcogenides

Transition metal dichalcogenides are materials of growing interest due to their unique electronic properties and rich phase diagram, offering promising opportunities for various applications. In this study, we investigate the optoelectronic characteristics of two-dimensional rhenium (Re)-based chalcogenides. These materials are composed of rhenium atoms sandwiched between chalcogen layers. In this paper, we have selected three rhenium-based chalcogenide (ReS2, ReSe2 and ReTe2) compounds in their 1T structure and calculated their electronic properties. Our study aims to find the intricacies of theoretical band structures and optical properties, aiming to assess their viability as semiconducting materials for the optoelectronics industry employing density funtional theory. Furthermore, we explore the impact of varying chalcogen compositions on the optoelectronic behavior, uncovering the tunability of these materials for specific applications. The study provides insights into the role of Re-based chalcogenides as promising candidates for emerging technologies, including photodetectors, solar cells, and other optoelectronic devices. The observed band gaps highlight the potential of these materials within the infrared region of the electromagnetic spectrum. After observing optical properties derived from our calculations, we discuss the corresponding potentials of the chosen materials in optoelectronic applications.

[formula omitted] First-principles calculations of optoelectronic characteristics of [formula omitted]&[formula omitted] doped [formula omitted] for energy renewable devices applications [formula omitted]

This research study investigates the structural and optoelectronic characteristics of Eu3+&Tb3+ doped BaSiO3 for energy renewable device applications, using FPLAW (full potential linear augmented plane wave) technique as applied in WIEN-2k code. The generalized gradient approximation has been utilized as the exchange-correlation functional for electrical and optical characteristic computations with Hubbard correction. Electronic characteristics demonstrate semiconducting nature, with a direct bandgap having a value of 1.1 eV for Eu3+ doped BaSiO3 and shows metallic nature, with bandgap 1.4 eV for Tb3+ doped BaSiO3. BaSiO3 Doped with Eu3+ and Tb3+ absorb ultraviolet photons substantially also reflect photons in infrared and visible wavelengths slightly. Such optical properties could be beneficial in optoelectronic device applications. When we doped the parent material, we observed overlap between the CB (conduction band) and VB (valence band), with many of them crossing near to the Fermi level. In electronic properties, for each doped material. The dielectric constant ε(ω), extinction coefficient K(ω), optical loss L(ω), refractive index n(ω), reflectivity R(ω) and absorption coefficient α(ω) being a function of incident photon energies were calculated to examine optical characteristics. BaSiO3 Doped with Eu3+ and Tb3+ absorb ultraviolet photons substantially also reflect photons in infrared and visible wavelengths slightly. Such optical properties could be beneficial in optoelectronic device applications.

K2Ag(Ga/In)Br6 lead-free HDPs: Investigation of the elastic, optoelectronic, optical coating, and thermal characteristics for thermoelectric and solar cells

In this study, an investigation of the structural stability, elastic, optoelectronic, thermoelectric, optical thin-film coating, and thermodynamic properties of K2Ag(Ga/In)Br6 (lead-free halide double perovskites, HDPs) was performed using first-principles calculations. The optimized structural parameters are in good agreement with the available data. Furthermore, Goldsmith's tolerance factor indicates an ideal value for both double perovskites, ensuring the structural stability of the cubic perovskites, and the elasticity parameters were analyzed to ensure the mechanical stability of the cubic phase. Direct and reduced band gaps of 0.4524 eV and 1.064 eV with semiconductor behavior are found for K2AgGaBr6 and K2AgInBr6, respectively, through adoption of the modified Becke–Johnson potential scheme. The absorption coefficient, refractive index, and dielectric function, as some of the optical properties, in addition to the optical thin-film properties, are well discussed, and the values suggest that these materials are promising candidates for different devices, such as optoelectronic and photovoltaic energy devices. In terms of the thermodynamics, the HDPs display favorable characteristics across various temperature and pressure ranges. Additionally, we assessed the thermoelectric properties, considering the power factor, Seebeck coefficient, thermal and electronic conductivities, and figure of merit. The current predictions suggest that these lead-free halide double perovskites have strong potential for application in thermoelectricity and photovoltaics.

Effect of capping rate on the performance of InAs/GaAs quantum dot solar cell

The GaAs capping layer significantly influences the structural and optoelectronic characteristics of the InAs quantum dot (QD). The capping rate modifies the essential parameters, such as size, shape, and composition, that determine the optical properties of the QDs. In this work, we present a theoretical model to study the effects of the capping rate on the absorption spectra of InAs dots embedded in the GaAs capping layer. The proposed model can be used for optimizing the structural and optical characteristics of InAs/GaAs QDs without using an annealing procedure or any capping material other than GaAs. In addition, the impact of three different GaAs capping layer growth rates on the performance of quantum dot solar cells is evaluated.

DFT molecular simulations for designing anthradithiophene-based photo and thermally stable solar cell compounds with enhanced fill factor, open-circuit voltage, and optoelectronic properties

The optoelectronic characteristics of fullerene-free photovoltaic compounds hold significant value in photonics and optoelectronics applications. To obtain the optimal candidate for modernized hi-tech purposes and to meet the rising requirement of photovoltaic blends for future solar cell applications, the current study centered on simulating and conducting DFT-analysis-of-synthesized anthradithiophene-based reference (RS) and nine tailored molecules (ZHS1–ZHS9). DFT and time-dependent-DFT methods were utilized to determine the photochemical, optoelectronic, and photovoltaic parameters such as absorption behavior, energy gaps, charge transfer capabilities, TDM analysis, reorganizational energy, charge transfer complex ZHS5:PC61BM study for ZHS1–ZHS9 and RS. The absorption maxima of ZHS1–ZHS9 molecules resulted in red shifting (680–816 nm) compared to the synthesized RS reference molecule (454 nm). The distribution of electron density on various molecular components is confirmed by the DOS and FMOs analysis. All tailored molecule possesses less energy gap, while ZHS5 gave the narrowest bandgap (1.21 eV) with less binding energy (0.19 eV) as well as excitation energy (1.02 eV) as compared to the reference molecule. The developed molecules carried larger open-circuit voltage (Voc = 1.04–1.88 V) and fill factor (FF=0.93) than the reference molecule Voc = 0.47 V and FF=0.803594, indicating that they are better suited to drawing more electric current. The ZHS5:PC61BM blend study and overall outcomes showed that these planned donor molecules are photo and thermally stable efficient solar cell candidates, and their ongoing research has the potential to result in high-performance photovoltaic systems. Thus, this work encouraged experimenters to create the suggested solar cell materials for cutting-edge optoelectronic high-tech uses.

Impact of Alternating-Current Operation on All-Inorganic Quantum Dot Light-Emitting Diodes.

In colloidal quantum dot light-emitting diodes (QD-LEDs), replacing organic hole transport layers (HTLs) with their inorganic counterparts is expected to yield distinct advantages due to their inherent material robustness. However, despite the promising characteristics of all-inorganic QD-LEDs, some challenges persist in achieving stable operation; for example, the electron overflow toward the inorganic HTL and charge accumulation within working devices return a temporal inconsistency in device characteristics. To address these challenges, we propose an operational approach that employs an alternating-current (AC) in all-inorganic QD-LEDs. We carry out comprehensive studies on the optoelectrical characteristics of all-inorganic QD-LEDs under direct-current (DC) or AC operation and demonstrate that AC operation can facilitate efficient charge carrier recombination within the QD emissive layer, leading to improved device efficiency and temporally invariant optoelectronic characteristics. Leveraging the intrinsic material robustness of inorganic charge transport layers (CTLs), our current study suggests a promising pathway toward enhancing the performance and stability of QD-LEDs, particularly for futuristic display applications.

Strain and orientation modulated optoelectronic properties of La-doped SrSnO3 epitaxial films

We have studied the structural, electrical, and optical properties of La0.05Sr0.95SnO3 thin films, which exhibited a strong dependence upon the substrate’s orientation and strain. X-ray diffraction results show that the LSSO films grow epitaxially on (001) and (011)-oriented LaAlO3 substrates, and the in-plane compressive strain decreases gradually upon increasing film thickness. Room-temperature resistivity varies from 4.23 (13.0) to 1.37 (4.76) mΩ cm as the film thickness increases for (001) orientation ((011) orientation). Temperature dependent resistivity curves of all the samples show a metal–semiconductor transition (MST), which can be explained by the electron–electron interactions below MST rather than weak localization. Both reducing the in-plane compressive strain and transferring the orientation from (011) to (001) can drive the MST point shifts toward lower temperature, indicative of the enhancement of the metallic transport in the films. The band gap increases upon increasing film thickness due to Burstein-Moss effect. The charge distributions of Sn and O from density functional theory (DFT) calculations illustrate that (001)-plane has a better conductivity. Furthermore, our DFT results also demonstrate that decreasing the in-plane strain will lead to a smaller electron effective mass, thus the increased carrier mobility can be obtained. These comprehensive investigations advance our knowledge of the optoelectronic characteristics and provide valuable insights for future research in related transparent materials.

Engineering optoelectronic properties of [formula omitted] superlattices using first principles method

Recent advancements in thin-film growth techniques have opened doors for engineering innovative heterostructures with ultra-thin layers. These artificial superlattices hold promise for novel optoelectronic devices. However, a complete understanding of their properties is crucial for optimal design. In this study, we employ the full-potential linearized augmented plane wave (FP−LAPW) approach based on density functional theory (DFT) to engineer the optoelectronic properties of (HgSe)n/(ZnTe)n superlattices by controlling the number of layers (n) in SLs; The exchange-correlation potential was calculated by the generalized gradient GGA approximation and the optoelectronics properties has adjusted by the Tran-Blaha modified Becke-Johnson (TB−mBJ) correction of GGA approximation. Our findings shed light on the significant influence of stacking periodicity on the optoelectronic properties of HgTe/ZnTe SLs. We demonstrate that manipulating layer count is a viable strategy for engineering their optoelectronic characteristics. Additionally, the predicted near-infrared absorption makes these SLs promising candidates for near-infrared detector applications.