Optoelectronic Characteristics Research Articles

Unraveling the influence of organic cations on tuning electronic structures and spin-splitting in two-dimensional layered organic-inorganic tin-iodine perovskites.

The solar cell and light-emitting device research community is currently focusing on investigating two-dimensional (2D) hybrid perovskite materials owing to their remarkable stability and intriguing optoelectronic characteristics, which hold significant promise for various applications. In general, the introduction of chirality in hybrid perovskites arises from symmetry breaking within their inorganic frameworks. Nevertheless, despite this understanding, the specific factors driving the observed increase in splitting remain obscure due to a lack of comprehensive investigations. Our research delves into the electronic properties of 2D layered hybrid perovskites, considering their behavior with and without spin-orbit coupling. We specifically focus on effect of Rashba splitting and the impact of electronic structure variation across a range of chiral perovskites by introducing chiral organic cations with differing degrees of π-conjugation, resulting in significant changes in spin-splitting magnitude. Systematic first principles investigations confirm that the distortion of the cage and d-spacing of chiral perovskites are crucial design parameters for achieving strong spin-splitting in 2D layered perovskites. Furthermore, our investigation reveals that these systems exhibit remarkable absorption capabilities in the visible light spectrum, as demonstrated by their computed optoelectronic characteristics. The chiral perovskites described in this study, which exhibit substantial spin-splitting, present a distinctive prototype with potential implications for spintronics and photovoltaics.

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

Fused Hexabenzocoronene-Porphyrin Conjugates with Tailorable Excited-State Lifetimes.

A new clear-cut strategy for fusing N-heterocyclic and carbon-pure systems is introduced en route to a versatile platform of multi-purpose tetrapyrrolic chromophores. In particular, three novel C-C bond-fused porphyrin-hexabenzocoronene (HBC) conjugates were synthesized under oxidative cyclodehydrogenation conditions, starting from tailor-made nickel porphyrin precursors. The fusion of the individual aromatic systems via 5-membered rings led to highly soluble π-extended porphyrins in excellent yields. The resulting porphyrin-HBC conjugates exhibit absorption cross-sections that are of interdisciplinary interest in the ever-growing field of organic photovoltaics and near-infrared (NIR) dyes. Quantum chemical calculations show that the newly formed 5-membered rings induce biradicaloid character in the porphyrin core, which has a strong impact on excited state lifetimes. This is confirmed by a thorough optoelectronic and time-resolved characterization in order to understand these unique features better. Broadened absorption characteristics go hand-in-hand with short-lived excited states with up to six orders of magnitude faster decay rates.

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

Optimizing Charge Transport and Band-Offset in Silicon Heterojunction Solar Cells: Impact of TiO2 Contact Deposition Temperature

Abstract 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.

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.

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.

Review about Organic-Inorganic Perovskite Single Crystal : Synthesis Methods, Properties and Applications

Due to their easy synthesis and exceptional optoelectronic characteristics, such as their long carrier diffusion length, high carrier mobility, low trap density, and tuneable absorption edge ranging from ultraviolet (UV) to near-infrared (NIR), perovskite single crystals have attracted a lot of attention in recent years. These properties have the potential to be used in solar cells, photo-detectors (PDs), lasers, and other devices. In this review provides detailed information about the synthesis methods and applications of perovskite single crystals.

First principles insight into the study of the structural, stability, and optoelectronic properties of alkali-based single halide perovskite ZSnCl3 (Z = Na/K) materials for photovoltaic applications.

Metal halide perovskites are crystalline materials with a sharp increase in popularity and rapidly becoming a major contender for optoelectronic device applications. In this work, we provide the optoelectronic features of a possible novel candidate, ZSnCl3 (Z = Na/K) Sn-based on a detailed numerical simulation. The output of the current computations is compared to the results that are currently available, and a respectable agreement is noted. The studied compounds were cubic in nature and structurally stabe. The mechanical properties reflectthe mechanical stability and ductility of the proposed materials. The Sn-based single perovskite compounds proposed in this study are mechanically stable and ductile. The narrow direct band gap for NaSnCl3 and KSnCl3 are 1.36 eV and 1.47 eV, respectively, using the HSE06 hybrid function with the Boltztrp2 integrated in Quantum ESPRESSO (QE) software. The effective use of these compounds in perovskite solar cells and other optoelectronic applications was confirmed by optical absorption spectral measurements conducted in the photon energy range of 0-20 eV.

Unraveling the synergism mechanistic insight of O-vacancy and interfacial charge transfer in WO3-x decorated on Ag2CO3/BiOBr for photocatalysis of water pollutants: Based on experimental and density functional theory (DFT) studies

Photocatalysis has been widely used as one of the most promising approaches to remove various pollutants in liquid or gas phases during the last decade. The main emphasis of the study is on the synergy of vacancy engineering and heterojunction formation, two widely used modifying approaches, to significantly alter photocatalytic performance. The vacancy-induced Ag2CO3/BiOBr/WO3-x heterojunction system has been fabricated using a co-precipitation technique to efficiently abate methylene blue (MB) dye and doxycycline (DC) antibiotic. The as-fabricated Ag2CO3/BiOBr/WO3-x heterojunction system displayed improved optoelectronic characteristic features because of the rational combination of dual charge transferal route and defect modulation. The Ag2CO3/BiOBr/WO3-x system possessed 97% and 74% photodegradation efficacy for MB and DC, respectively, with better charge isolation and migration efficacy. The ternary photocatalyst possessed a multi-fold increase in the reaction rate for both MB and DC, i.e., 0.021 and 0.0078 min−1, respectively, compared to pristine counterparts. Additionally, more insightful deductions about the photodegradation routes were made possible by the structural investigations of MB and DC using density functional theory (DFT) simulations. This study advances the understanding of the mechanisms forming visible light active dual Z-scheme heterojunction for effective environmental remediation.

Tunneling assisted p-contact free GaN-InGaN green light-emitting diodes

The effects of bottom tunnel junction (TJ) on optoelectronic characteristics of green light-emitting diodes are analyzed numerically. Our proposed LED has enhanced internal quantum efficiency (IQE), radiative recombination rate, and carrier concentration in comparison to reference conventional LED. The IQE increases by 17%, droop is reduced by 28%, and emission intensity is nearly twice as high as than reference design. The improved optical properties of the proposed structure are due to excellent carrier confinement and altered spontaneous polarization in the vicinity of the active region by TJ.

A Fluorescent Conjugated Polar Polymer for Probing Charge Injection in Multilayer Organic Light-Emitting Transistors.

Ambipolar organic light-emitting transistors (OLETs) are extremely appealing devices for applications from sensing to communication and display realization due to their inherent capability of coupling switching and light-emitting features. However, their limited external quantum efficiency (EQE) and brightness under ambipolar bias conditions hamper the progress of OLET technology. In this context, it was recently demonstrated in multi-stacked devices that the engineering of the interface between the topmost electron-transporting organic semiconductor (e-OS) and the emission layer (EML) is crucial in optimizing the recombination of the minority charges (i.e., electrons) and to enhance EQE and brightness. Here, we introduce a new light-emitting conjugated polar polymer (CPP) in a multi-stacked OLET to improve the electron injection from e-OS to EML and to study, simultaneously, electroluminescence-related processes such as exciton formation and quenching processes. Interestingly, we observed that the highly polar groups present in the conjugate polymer induced polarization-related relevant charge-trapping phenomena with consequent modulation of the entire electrostatic field distribution and unexpected optoelectronic features. In view of the extensive use of CPPs in OLETs, the use of multifunctional CPPs for probing photophysical processes at the functional interfaces in stacked devices may speed up the improvement of the light-emission properties in OLETs.

Synergistic charge-transfer dynamics of rigid fused and unfused backbone with donors lead to promising photovoltaic properties of diazaborinine-based chromophores

Herein, a series of diazaborinin based derivatives (FABD1–FABD8) having D-π-D configuration was designed by inserting different types of rigid fused and unfused π-bridges into reference molecule (FABR) to explore their photovoltaic characteristics. To determine the optoelectronic and charge transport characteristics of these analogues, DFT/TD-DFT based calculations were conducted at the MPW1PW91/6-31G (d,p) level. For this, various analyses were performed such as transition density matrix (TDM), global reactivity parameters (GRP), open-circuit voltage (Voc), optical properties (UV–Vis), binding energy (Eb), hole-electron and frontier molecular orbital (FMO) energies. Their insights indicate that a rigid fused π-bridge greatly lowers the band gap as compared to an unfused π-spacers. Particularly, FABD7 showed the lowest energy gap of 2.20 eV owing to the presence of a rigid fused central core as compared to FABR with a band gap of 2.65 eV. Similarly, the entitled designed derivatives demonstrated a redshift absorption in the range of 585.7–704.6 nm while FABR is reported with 558.7 nm in the solvent phase. Furthermore, these derivatives displayed significant Voc with blending of PC61BM acceptor. This observation was also supported by DOS and TDM based insights. Interestingly, FABD7 seemed as a viable photovoltaic material due to its strong optical properties and small band gaps. These results uncover that the designed chromophores may be considered as efficient to enhance the performance of OSCs.

Theoretical study of lead-free mixed-valence mixed-halide Au-based perovskites for optoelectronics

Inorganic mixed-valence Au-based perovskites have received considerable attention due to their nontoxic elements, good stability and superior properties. Hence it is of significant interest to explore more novel Au-based perovskite materials for solar cell applications. This study presents a detailed theoretical exploration on the structural features, thermodynamic and mechanical stability, optoelectronic characteristics, and photovoltaic performance of Cs2AuIAuIIICl6-xBrx, Cs2AuIAuIIICl6-xIx, and Cs2AuIAuIIIBr6-xIx (x = 2, 4) in comparison with that of Cs2AuIAuIIIX6 (X = Cl, Br, I). Through the comprehensive evaluation of thermodynamic and mechanical stability, Cs2AuIAuIIIX2Y4 (X2Y4Cl2Br4, Cl2I4, and Br2I4) is identified to be stable. The impact of anion substitution on the electronic characteristics of these mixed-halide Au-based perovskites is thoroughly disclosed. It is observed from band structure calculations that Cs2AuIAuIIIX4Y2 (X4Y2Cl4Br2, Cl4I2, and Br4I2) exhibits a lower direct-gap within 0.7–1.0 eV, while Cs2AuIAuIIIX2Y4 (X2Y4Cl2Br4, Cl2I4, and Br2I4) possesses an indirect-gap with ∼1.1 eV. The nonlinear band gap variation is disclosed and reasonably explained. Furthermore, Cs2AuIAuIIIX2Y4 displays strong dipole-allowed visible-light absorption. In addition, the simulated efficiency of Cs2AuIAuIIIX2Y4 is within ∼28–30 %, which is comparable to those of GaAs and CH3NH3PbI3. This theoretical exploration is helpful for developing more novel inorganic Au-based perovskites with desirable photovoltaic performance.

Optoelectronic, thermoelectric and 3D-Elastic properties of lead-free inorganic perovskites CsInZrX6 (I, Cl and Br) for optoelectronic and thermoelectric applications

Halide perovskite materials have recently gained worldwide attention since they offer a new cost-effective way to generate renewable and green energy. In the current work, the structural, electrical, elastic, optical and thermoelectric properties of new perovskites CsInZrX6 (I, Cl and Br) were explored by density-functional theory (DFT). The results indicated that the computed lattice parameters agree really well with the current experimental and theoretical results. Moreover, the band structure profile strongly suggests that the compounds exhibit a semiconducting nature with a direct band gap. The analysis of their optical properties reveals that the perovskites possess a low reflectivity (below 23%) and a high optical absorption coefficient (106 cm−1). This is also supported by the evaluation of their calculated elastic constants and their related parameters in cubic structure which show that these compounds are brittle, mechanically stable and possess covalent bonds. On the other hand, in addition to exhibiting outstanding optoelectronic and mechanical characteristics, CsInZrCl6 also possesses dynamical stability, making it a promising candidate for application in various optoelectronic devices except for solar cells due to its relatively large bandgap. Furthermore, the BoltzTraP software was used to compute the materials’ thermoelectric properties, with the computed values of the figure of merit (ZT) for CsInZrBr6, CsInZrCl6 and CsInZrI6 being 0.76, 0.73 and 0.725, respectively. This is also a strong indication that these materials are potential for thermoelectric applications.