Optoelectronic Characteristics Research Articles

Optical, Electrical, and Optoelectronic Characterization of Ti‐Supersaturated Gallium Arsenide

Herein, a detailed investigation on the properties of supersaturated gallium arsenide (GaAs) using Ti+ implantation followed by nanosecond pulsed laser melting (PLM) is presented. The supersaturated samples are analyzed by means of electrical, optical, and optoelectronic characterization. The sheet resistance results obtained using van der Pauw configuration measurements do not show activation of the implanted Ti+ in semi‐insulating GaAs after PLM. Absorptance measurements show a sub‐bandgap absorption (up to 6.5% for λ = 1000 nm) of the supersaturated GaAs:Ti and the just PLM‐processed GaAs, with the same laser melting fluence used (0.50 J/cm−2). The origin of this sub‐bandgap absorption is analyzed. Optoelectronic measurements show a similar sub‐bandgap photo‐response related to the absorption analyzed. The photo‐response measured below the bandgap originates from point defects introduced by the PLM process.

Sn-doped Ag2S nanostructures: Sonochemical synthesis and enhanced optoelectronic performance for solar-range and self-powered photodetector applications

The current investigation explored the impact of tin (Sn) doping at various concentrations on the physical and optoelectronic characteristics of silver sulfide (Ag2S) nanostructures synthesized through the ultrasonication method. Their capability as a photodetector was also assessed. The findings indicated an increase in crystallite size and lattice strain. Microscopic images depicted that the introduction of Sn concentrations reduced the size of Ag2S nanostructures while preserving their spherical morphology. Results demonstrated increasing of absorption intensity and carrier concentrations with addition of Sn concentrations. The analysis of current-voltage curves elucidated the charge transport mechanism. Additionally, the optoelectronic properties evolved, revealing that Sn doping enhances the quality parameters of Ag2S nanostructures, rendering it a more effective self-powered photodetector in the solar spectrum.

Experimental evidence for defect tolerance in Pb-halide perovskites

The term defect tolerance (DT) is used often to rationalize the exceptional optoelectronic properties of halide perovskites (HaPs) and their devices. Even though DT lacked direct experimental evidence, it became a "fact" in the field. DT in semiconductors implies that structural defects do not translate to electrical and optical effects (e.g., due to charge trapping), associated with such defects. We present pioneering direct experimental evidence for DT in Pb-HaPs by comparing the structural quality of 2-dimensional (2D), 2D-3D, and 3D Pb-iodide HaP crystals with their optoelectronic characteristics using high-sensitivity methods. Importantly, we get information from the materials' bulk because we sample at least a few hundred nanometers, up to several micrometers, from the sample's surface, which allows for assessing intrinsic bulk (and not only surface-) properties of HaPs. The results point to DT in 3D, 2D-3D, and 2D Pb-HaPs. Overall, our data provide an experimental basis to rationalize DT in Pb-HaPs. These experiments and findings will help the search for and design of materials with real DT.

Self-Assembly-Induced Enhancement of Cathodic Electrochemiluminescence of Copper Nanoclusters for a Split-Type Matrix Metalloproteinase 14 Sensing Platform.

The unique optoelectronic and tunable luminescent characteristics of copper nanoclusters (Cu NCs) make them extremely promising as luminophores. However, the limited luminescence intensity and stability of Cu NCs have restricted their application in the field of electrochemiluminescence (ECL). Herein, a self-assembly-induced enhancement strategy was successfully employed to enhance the cathodic ECL performance of flexible ligand-stabilized Cu NCs. Specifically, Cu NCs form ordered sheetlike structures through intermolecular force. The restriction of ligand torsion in this self-assembled structure leads to a significant improvement in the ECL properties of the Cu NCs. Experimental results demonstrate that the assembled nanoscale Cu NC sheets exhibit an approximately three-fold increase in cathodic ECL emission compared to the dispersed state of Cu NCs. Furthermore, assembled nanoscale Cu NCs sheets were utilized as signal probes in conjunction with a specific short peptide derived from the catalytic structural domain of matrix metalloproteinase 14 (MMP 14) as the identification probe, thereby establishing a split-type ECL sensing platform for the quantification of NMP 14. The investigation has revealed the exceptional performance of assembled nanoscale Cu NCs sheets in ECL analysis, thus positioning them as novel and promising signal probes with significant potential in the field of sensing.

DFT study of optoelectronics and transport properties of double perovskites Cs2YCuX6 (X = Cl, Br, I) for energy conversion devices

Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs2YCuX6 (X = Cl, Br, I) DPHs. The elastic constants and phonon dispersion curves reveal ductile nature and mechanical and thermodynamic stability of the examined materials. The Born stability criteria ensures structural stability, while the formation energy ranging from −2.28 to −1.68 eV signifies thermodynamic viability. Furthermore, the thermodynamic stability of investigated double perovskites Cu2YCuX6 (X = Cl, Br, I) have been verified by performing ab-initio finite temperature molecular dynamics (MD) simulation. The examination of mechanical characteristics affirms the ductile nature of the material, and its substantial anisotropic factor enhance its significance for device fabrication. The band gaps calculated at 2.65 eV, 2.55 eV, and 2.45 eV from band structures, highlight the significance of the studied double perovskites (DPs) for optoelectronic applications. Optical parameters yield information on minimal dispersion and expansive absorption band. Additionally, transport characteristics are analyzed through parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity, and the Figure of merit (ZT).

C3N based heterobilayers: a potential platform to explore optoelectronic and thermoelectric properties

We theoretically investigate the full thermal transport and optoelectronic features of two established van der Waals heterostructures based on the recently synthesized monolayer of C3N using the machinery of the Boltzmann transport equation and GW+BSE calculations. Among the structures, C3N/hBN tends to exhibit a small indirect gap semiconducting nature with an admixture of comparatively higher ‘flat-and-dispersiveness’ and band degeneracy in the conduction band minima. A nearly comparable high thermoelectric power factor is observed for both carrier types at 300 K and 900 K at specific concentrations. The other material, C3N/Graphene however maintains a low Seebeck coefficient with large electrical conductivity which correctly manifests its metallic character. A combination of low atomic mass, higher anharmonicity and longer lifetime of acoustic phonons in C3N/hBN results in an intermediate lattice thermal conductivity (196 W m−1 K−1) at room temperature as compared to its constituent monolayers. Under heavy n-type doping, C3N/hBN hetero-bilayer displays a figure of merit value of 0.13 (and 0.36) at room temperature (and at 900 K). As per the optical signatures are concerned, C3N/hBN reveals two distinct absorption peaks with a high electron–hole quasiparticle interaction energy correction. Besides both the heterostructures display a much better absorption throughout the spectrum as compared to graphene. We expect these findings will motivate future research in designing thermoelectric and optoelectronic materials made of light mass, earth-abundant and non-toxic elements.

First-principles prediction of antimony based XSbF3 (X = Be, Mg, Ca and Sr) fluoroperovskites: An insight into structural, optoelectronic and thermal properties

First-principles computations have been carried out to explore the structural, optoelectronic and thermodynamic characteristics of antimony-based fluoroperovskites XSbF3 (X = Be, Mg, Ca, Sr) compounds. The optimized lattice constants of 4.46, 4.60, 4.72 and 4.81 Å are obtained for BeSbF3, MgSbF3, CaSbF3 and SrSbF3 compounds, respectively. The negative values of the binding energy of these compounds advocate that these compounds are structurally and thermodynamically stable. The electronic properties such as band structures, density of states and partial density of states reveal the metallic character of the studied compounds. Various optical and thermal parameters have been discussed in detail. To the best of our knowledge, this is the first theoretical attempt to study the physical properties of XSbF3 (X = Be, Mg, Ca, Sr) fluoroperovskite compounds. The findings of this study yield useful insights into the potential implementation of these compounds for the development of lenses, anti-reflection coatings and other valuable optoelectronic devices.

Proliferating optoelectronic properties of doped ZnO nanoparticles

Ag-doped ZnO nanocomposites were synthesized precisely by adopting a wet chemical method to explore their optoelectronic characteristics for LED applications. Characterization studies have progressed for substantiation of its structural, and functional characteristics in conjugation with the optical properties of nanocomposites before and after doping. The metal-oxygen bonding was affirmed from IR spectra and excitation characteristics were detailed from UV–visible absorption spectra. The SEM images along with Energy dispersive X-ray analysis deliberates hexagonal morphology for pure ZnO which was surprisingly reformed into poly hexagon structures after doping with silver ions. The pertinence of the target material for LED application was verified by performing photoluminescence and charge density measurements. The doping of silver ions into ZnO presents a novel avenue in the field of optronics and serves as appropriate phosphors for light-emitting diodes. The application of the title compound was established by providing nano coating to LED bulb and emission efficiencies was recorded before and after coating. The present research recommends a unique method of nanocoating of LED bulb for efficient light intensity.

A DFT approach to explore the structural, optoelectronic, mechanical, and thermoelectric attributes of lead-free RbInX3 (X = I, Br, Cl) halide perovskites for renewable energy applications

Halide perovskites are significant due to their versatility and high performance in optoelectronics and green technologies. This paper thoroughly investigates the structural, elastic, optoelectronic and transport characteristics of RbInX3 (X = I, Br, Cl) perovskites using density functional theory (DFT) embedded in Wein2K. Modified Becke Johnson as an exchange correlation potential is used to evaluate the physical characteristics. Structural stability is achieved with the tolerance factor and octahedral tilting along with the optimization curves. A metallic character is detected in RbInI3. However, the replacement of I with Br and Cl atoms results in an indirect band gap of 0.9 eV and 1.95 eV at (L-X) symmetry points, respectively. The elastic constants are utilized to determine the elastic parameters that ensure the structural stability of perovskites. Cauchy pressure and Poisson’s ratio indicate the ductile nature of all studied phases. The thermal behavior is evaluated through the computation of Debye temperature. Furthermore, an insight into the material’s interaction with electromagnetic radiation is accessed through the optical parameters. A high absorption at 1.49 eV for RbInI3, 1.65 for RbInBr3 and 2.57 for RbInCl3 show their potential for light emitting devices. The semi-classical Boltzmann theory is employed to compute thermoelectric properties, which show RbInI3, RbInBr3 and RbInCl3 possess high electrical conductivities of 3.068 ×1019 S m–1, 1.88 ×1019 S m–1 and 1.76 ×1019 S m–1 at 1200 K, respectively. The ZT value for RbInBr3 is 0.74 and RbInCl3 is 0.73, while RbInI3 exhibit the lowest ZT of 0.04 at 1200 K. The examined characteristics indicate that RbInBr3 and RbInCl3 possess promising potential for renewable energy applications.

DFT study of mechanical, optoelectronic, and thermoelectric characteristics of double perovskites Li2CuTiZ6 (Z = Cl, Br, I) for energy harvesting technology

Recent studies have produced stable inorganic perovskites that contain no lead, replacing lead-containing perovskites' risky and unstable properties. The present investigation thoroughly examined the electrical behavior, elastic characteristics, optical features, and transport properties of Li2CuTlZ6 (Z = Cl, Br, I) halides in order to discover potential applications. The Wien2k code was utilized to apply density functional theory (DFT) in order to clarify these physical properties. Using the generalized gradient approximation (PBEsol-GGA), we determined structural parameters through the energy optimization procedure that corresponded with the available data. Additionally, elastic parameters as well as formation energies ranging between -2.33 to -1.39 eV were used to validate cubic durability for the two halides. Moreover, the modified Becke-Johnson (mBJ) potential successfully provided precise direct bandgap values for all halides. According to this study, the shift in anions from Cl to Br is responsible for the reduction in band gap within the infrared spectrum. Our computed optical parameter findings show that Li2CuTlCl6 and Li2CuTlBr6 halides demonstrate excellent optoelectronic efficiency with low reflection, strong optical absorption, and conductivity. The investigation clarifies that the temperature-dependent character of the materials electrical transport properties is due to their very small bandgap. These materials may find use in thermoelectric applications, as evidenced by the almost unity of the obtained figure of merit, which points to their semiconducting behaviour.

Optoelectronic Material Characterization Platform using RF Topological Edge States

AbstractEfficient characterization of optoelectronic material properties represents a crucial step in the development of next‐generation infrared (IR) materials and devices. For the first time, a sensitive, contact‐free optoelectronic material characterization platform is demonstrated that exploits the unique properties of radio frequency (RF) topological edge states implemented in a topological microstrip waveguide. The topological device is compatible with standard printed circuit board (PCB) processes with no additional materials, stubs, or resonators. The waveguide and topological properties computationally are designed and then experimentally the results are validated with S‐parameter and near‐field measurements. Finally, as a proof of principle, the room temperature spectral response of a micron‐scale thick mid‐wave infrared (MWIR) mercury cadmium telluride (Hg0.70Cd0.30Te) is measured using the topological microstrip and a five‐fold and 20‐fold increase is demonstrated in response when compared to a plain microstrip and trivial bandgap device, respectively. These results open the door to straightforward, low‐cost characterization of optoelectronic films.

Chemically tuned intermediate band states in atomically thin CuxGeSe/SnS quantum material for photovoltaic applications.

A new generation of quantum material derived from intercalating zerovalent atoms such as Cu into the intrinsic van der Waals gap at the interface of atomically thin two-dimensional GeSe/SnS heterostructure is designed, and their optoelectronic features are explored for next-generation photovoltaic applications. Advanced ab initio modeling reveals that many-body effects induce intermediate band (IB) states, with subband gaps (~0.78 and 1.26 electron volts) ideal for next-generation solar devices, which promise efficiency greater than the Shockley-Queisser limit of ~32%. The charge carriers across the heterojunction are both energetically and spontaneously spatially confined, reducing nonradiative recombination and boosting quantum efficiency. Using this IB material in a solar cell prototype enhances absorption and carrier generation in the near-infrared to visible light range. Tuning the active layer's thickness increases optical activity at wavelengths greater than 600 nm, achieving ~190% external quantum efficiency over a broad solar wavelength range, underscoring its potential in advanced photovoltaic technology.

Reduced phonon coupling via controlled defect levels in blue emitting CsPbBr3 nanoplatelets

Metal-halide perovskites (MHPs) are promising materials for light-emitting diodes (LEDs) because of their high color purity, wide gamut, and low-cost processing. However, blue-emitting MHP LEDs exhibit low external quantum efficiencies because they are more susceptible to defect states with a larger energy bandgap compared to their green and red counterparts. Current strategies for achieving blue-emitting MHP LEDs involve compositional engineering; however, the ion migration of mixed halides imposes significant challenges related to abundant trap states. Therefore, in this study, we systematically investigated the effects of short organic and inorganic ligands with characteristic molecular structures and adjacent moieties on the optoelectronic characteristics of low-dimensional CsPbBr3 nanoplatelets (NPLs) used as blue emitters in PeLEDs. Inorganic ligand (i.e., hydrazine monohydrobromide; HZBr) treatment achieved the most significant photoluminescence enhancement (∼10 fold) while preserving crystalline morphology and colloidal stability. Temperature-dependent photophysical properties reveal that HZBr treatment eliminates band tail states arising from lower defect levels in highly confined CsPbBr3 NPLs. Therefore, it suppresses defect trapping and electron–phonon coupling, thereby reducing thermal quenching properties. The HZBr-treated NPLs were integrated into blue perovskite LEDs and demonstrated a narrow emission peak at 471 nm.

Tailoring the optoelectronic properties of monolayer BA2PbI4/MoS2 heterojunction through terminal variations and defect engineering

In light of the inherent challenge posed by the simultaneous pursuit of structural stability and favorable optoelectronic characteristics in two-dimensional organic-inorganic halide perovskites, the construction of heterojunctions emerges as a promising strategy for mitigating electronic deficiencies and enhancing overall performance. Furthermore, defect engineering stands as a commonly employed technique to fine-tune the photoelectric properties of materials. In this study, we systematically investigate the pivotal vacancy defects, namely VBA and VI, within the monolayer BA2PbI4/MoS2 heterojunction system, employing first-principles calculations. Our computational findings illuminate the conductivity of MoS2 can be modulated when it interfaces with distinct surface terminations of 2D BA2PbI4, thereby exerting influence over electron flow within MoS2. Additionally, we observe a progressive transformation of p-type doped MoS2 into a heavily doped material as the concentration of BA vacancy defects increases. To further optimize the optoelectronic properties, we strategically introduce the I vacancy (Pb-Pb dimer) defect, effectively transitioning the indirect bandgap heterojunction into a direct one. Our study underscores the profound impact of different surface terminations and defect configurations on the physical attributes of the heterojunction, offering valuable insights for the fabrication of high-performance photoelectric materials.

Optical design and bandgap engineering in ultrathin multiple quantum well solar cell featuring photonic nanocavity

AbstractUltrathin solar cells are efficient and captivating devices with unique technological and scientific features in terms of minimal material consumption, fast fabrication processes, and good compatibility with semi‐transparent applications. Such photovoltaic (PV) technologies can enable effective synergy between optical and electronic confinements with large tuning capabilities of all the optoelectronic characteristics. In this work, the implications of the optical design and the bandgap engineering in ultrathin hydrogenated amorphous Si/Ge multiple quantum well (MQW) solar cells featuring photonic nanocavity are analyzed based on experimental measurements and optoelectronic modelling. By changing the period thicknesses and the positions of QWs inside the deep‐subwavelength nanophotonic resonator, the spatial and spectral distributions of the optical field and the local absorption are strongly affected. This leads to a modulation of the absorption resonance condition, the absorption edge and the resulting photocurrent outputs. Because of quantum confinement effect, the change of MQW configurations with different individual QW periods while keeping similar total thickness of about 20 nm alters both the bandgap energy and the band offset at the QW/barrier heterojunctions. This in turn controls the photovoltage as well as the carrier collection efficiency in solar cells. The highest open circuit voltage and fill factor values are achieved by employing MQW device configuration with 2.5 nm‐thin QWs. A record efficiency above 5.5% is reached for such emerging ultrathin Si/Ge MQW solar cell technology using thinner QWs with sufficient number, because of the optimum trade‐off between all the optoelectronic characteristic outputs. The presented design rules for opaque ultrathin solar cells with quantum‐confined nanostructures integrated in a photonic nanocavity can be generalized for the engineering of relevant multifunctional semitransparent PV devices.

Effect of metal (Cr, Sr, Ag, Cu) doping on the performance of lead-free RbSnI3 based perovskite solar cells: A theoretical approach

Perovskite solar cells based on lead have witnessed unprecedented growth over the past decade, achieving an impressive power conversion efficiency (PCE) of 26.1%. However, lead toxicity remains a concern for commercialization. In order to resolve the matter, scientists have been investigating alternative materials; in this context, rubidium-based lead-free perovskites like RbSnI3 may be a promising alternative because it has a high optical conductivity and absorption coefficient. Density Functional Theory (DFT)-based first-principles studies are used in this work to examine the effect of metal doping (specifically Cr, Sr, Ag, and Cu) on the optoelectronic and structural characteristics of orthorhombic RbSnI3 perovskite. In addition, we conducted a comprehensive study to investigate the impact of metal doping on the formation energy, structural stability, and HOMO–LUMO energy levels of RbSnI3 perovskite. Introducing transition metal cations (Cr2+, Ag+, and Cu+) at the Rb site results in a flat band in the conduction band region, transforming the RbSnI3’s indirect band gap into a direct one and significantly affecting the optoelectronic properties. The DFT results are then integrated into the Solar Cell Capacitance Simulator (SCAPS-1D) to estimate the effectiveness of the modeled device. The Cu-doped RbSnI3 device exhibits the highest PCE of 20.2%. Furthermore, Ag and Cu doping in RbSnI3 increases bond length, which reduces exciton binding energy and helps with charge carrier generation.

Facile metal-free synthesis of thiazolo[5,4-d]thiazole-containing conjugated polymers for thin-film electronics

Herein, we report the facile metal-free polycondensation reaction between dicarbonyl derivative and dithioxamide for the synthesis of thiazolo[5,4-d]thiazole-based semiconductor polymer. We showed that the polymers obtained by classical Suzuki or Stille reactions and proposed metal-free polycondensation possess similar optoelectronic and physicochemical characteristics. Their application as hole-transport layers in perovskite solar cells (PSCs) showed that the polymer obtained by an alternative method provides comparable or even slightly higher performance of devices. These results illustrate availability of organic semiconductor materials via alternative green and sustainable polycondensation reaction for the state-of-the-art photovoltaic technologies.

Ab initio analysis of structural, optoelectronic, thermoelectric, and elastic characteristics of K2MBiBr6 (M = Na, Ag, and Cu) for green energy

Ab initio analysis of structural, optoelectronic, thermoelectric, and elastic characteristics of K2MBiBr6 (M = Na, Ag, and Cu) for green energy

Elastic, Optoelectronic, and Photocatalytic Characteristics of Semiconducting Cesium Niobium Oxide: First Principles Analysis

Elastic, Optoelectronic, and Photocatalytic Characteristics of Semiconducting Cesium Niobium Oxide: First Principles Analysis

Out‐Of‐Phase Articulation Strategy of CsPbBr3/CsPb2Br5 Perovskite for High Sensitivity X‐Ray Detection

AbstractPolycrystalline CsPbBr3 perovskite materials exhibit exemplary stability, and desirable optoelectronic characteristics are promising for direct X‐ray detection. In this study, polycrystalline 2D phase of CsPb2Br5 hinged on CsPbBr3 is investigated for X‐ray array detector. The incorporation of CsPb2Br5 will modify the carrier transport environment, acting as an amplification factor that significantly enhances carrier mobility and response sensitivity. Finally, the devices demonstrates excellent performance growth. Carrier mobility of CsPbBr3 is improved by a significant 2 orders of magnitude, leading to the sensitivity increased from 2.64 × 104 to 2.58 × 105 µC Gyair−1 cm−2 at a bias voltage of 25 V mm−1. Even at a low bias voltage of 2 V mm−1, still got the value of 3.075 × 103 µC Gyair−1 cm−2, accompanied by a notable increase in the minimum detection limit of 127.9 nGyair s−1 at 0.5 V. Furthermore, a high modulation transfer function (MTF) of 1.57 lp mm−1 is obtained, and achieved a clear and high contrast X‐ray imaging with 64 × 64 TFT board. The perovskite exhibits outstanding light stability (RH ≈ 70 ± 5%) in the atmosphere following the introduction of 2D phase. This excellent carrier transport effect and good long‐term stability present significant commercial potential.