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Functionalization of perovskite nanocrystal surfaces with thiocyanate anions presents a transformative approach to enhancing stability and photoluminescence quantum yield (PLQY) through surface defect passivation. This study investigates the role of thiocyanate ligands in modifying the optoelectronic properties of CsPbBr3 nanocrystals. We employed ultrafast two-dimensional infrared spectroscopy to investigate the nature of the dynamic interaction of thiocyanate ligands with nanocrystal surfaces, providing insights into the mechanisms underlying the observed increase in PLQY and stability. Our analysis reveals that the thiocyanate ligands efficiently passivate the surface defects, thereby enhancing the PLQY and the stability of the treated nanocrystals. The spectroscopic evidence supports a model where thiocyanate binds to under-coordinated lead atoms, contributing to a stable nanocrystal surface with enhanced optoelectronic performance. This ligand-induced passivation mechanism advances our understanding of surface chemistry's role in optimizing nanomaterials for solar cell and LED applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) hold immense promise as ultrathin-body semiconductors for cutting-edge electronics and optoelectronics. In particular, their sustained charge mobility even at atomic-level thickness as well as their absence of surface dangling bonds, versatile band structures, and silicon-compatibility integration make them a prime candidate for device applications in both academic and industrial domains. Despite such high expectations, group-VI TMDs reportedly exhibit a range of enigmatic properties, such as substantial contact resistance, Fermi level pinning, and limited unipolar charge transport, which are all rooted in their inherent defects. In other words, intrinsic physical properties resulting from their native defects extend their influence beyond the material level. Bridging point-defect-induced material properties and their behavior at the device level, this Perspective sheds light on the significance of crystalline defects beyond a rather simple defect–property relationship. As a distinctive approach, we briefly review the well-established defect model of conventional III–V semiconductors and further apply it to the emergent defect behaviors of 2D TMDs such as their defect-induced gap states. Within the main discussion, we survey a range of behaviors caused by the most prevalent intrinsic defect, namely, vacancies, within 2D TMDs, and their implications for electronic and optoelectronic properties when employed at the device level. This review presents an in-depth summary of complexities in material properties as well as device characteristics arising from intrinsic point defects and provides a solid foundation for the cross-links among native defects and material/device properties. [ABSTRACT FROM AUTHOR]

This work investigates exciton localization and dynamics in semiconductor GaNAsP nanowires (NWs) with varying nitrogen concentrations. Through detailed time-resolved photoluminescence studies, we identify a nitrogen composition-dependent difference in exciton transfer between localized states formed due to alloy disorder. With [N] = 0.1%, the localized states exhibit cluster-like, non-interacting behavior, whereas at [N] = 1.1%, a continuous band of localized states is observed. Additionally, the phosphorous incorporation in the NWs appears to enhance the exciton spatial confinement compared to behaviors observed in phosphorous-free GaNAs NWs, emphasizing the role of the alloy composition in the nature of exciton localization. Temperature is highlighted as a significant factor affecting exciton mobility, enabling efficient transfer between the localized states at higher temperatures. This, in turn, influences exciton lifetimes. Our findings, therefore, shed light on the nature of exciton dynamics in GaNAsP NWs, enriching our understanding of these materials and paving the way for their applications in optoelectronics. [ABSTRACT FROM AUTHOR]

Chiral hybrid lead halide perovskites show interesting chiral optoelectronic properties. The extent of chirality is often estimated by their circular dichroism (CD) response. Here, we show that the CD data depend strongly on film morphology. Four of the six chiral hybrid lead halide films prepared, 2D (R- and S-MBA)2PbI4 and 1D (R- and S-MBA)PbI3 (MBA: methylbenzylammonium), form homogenous non-textured films and show an isotropic CD signal. In contrast, the other two samples, 1D (R- and S-MBA)PbBr3, form textured films, showing uncorrelated CD signals from different parts of the film. Therefore, the role of film morphology needs to be verified before designing and comparing the chiroptic and chiral optoelectronic properties of hybrid perovskites. [ABSTRACT FROM AUTHOR]

Nanosheets of transition metal dichalcogenides with prospects of photocatalysis and optoelectronics applications have significant potential in device fabrication due to their low-cost production and easily controllable morphology. Here, non-degenerate pump-probe differential transmission studies with varying pump-fluence have been carried out on single-phase 2H–MoSe2 and mixed-phase 1T/2H–MoSe2 nanosheets to characterize their excited carrier dynamics. For both the samples, the differential probe transmission data show photo-induced bleaching at earlier pump-probe delay followed by photo-induced absorption unveiling signatures of exciton-state filling, exciton trapping, defect-mediated photo-induced probe absorption and recombination of defect bound excitons. The exciton trapping and photo-induced absorption by the trapped-carriers are estimated to occur with time constant of ∼430 to 500 fs based on multi-exponential modelling of the differential transmission till pump-probe delay of ∼3.5 ps. Biexponential modeling of the subsequent slow-recovery of the negative differential transmission at pump-probe delay ≳3.5 ps reveals that the exciton recombination happens via two distinct decay channels with ∼25 to 55 ps (τ1) and ≳1 ns (τ2) time constants. Pump-fluence dependent reduction in τ1 and further modelling of exciton population using higher order kinetic rate equation reveals that the two-body exciton-exciton annihilation governs the exciton recombination initially with a decay rate of ∼ 10 − 8 cm3s−1. The detailed analysis suggests that the fraction of total excitons that decay via long decay channel decreases with increasing exciton density for 2H–MoSe2, in contrast to 1T/2H–MoSe2 where the fraction of excitons decaying via long decay channel remains constant. [ABSTRACT FROM AUTHOR]

Nanosheets of transition metal dichalcogenides with prospects of photocatalysis and optoelectronics applications have significant potential in device fabrication due to their low-cost production and easily controllable morphology. Here, non-degenerate pump-probe differential transmission studies with varying pump-fluence have been carried out on single-phase 2H–MoSe2 and mixed-phase 1T/2H–MoSe2 nanosheets to characterize their excited carrier dynamics. For both the samples, the differential probe transmission data show photo-induced bleaching at earlier pump-probe delay followed by photo-induced absorption unveiling signatures of exciton-state filling, exciton trapping, defect-mediated photo-induced probe absorption and recombination of defect bound excitons. The exciton trapping and photo-induced absorption by the trapped-carriers are estimated to occur with time constant of ∼430 to 500 fs based on multi-exponential modelling of the differential transmission till pump-probe delay of ∼3.5 ps. Biexponential modeling of the subsequent slow-recovery of the negative differential transmission at pump-probe delay ≳3.5 ps reveals that the exciton recombination happens via two distinct decay channels with ∼25 to 55 ps (τ1) and ≳1 ns (τ2) time constants. Pump-fluence dependent reduction in τ1 and further modelling of exciton population using higher order kinetic rate equation reveals that the two-body exciton-exciton annihilation governs the exciton recombination initially with a decay rate of ∼ 10 − 8 cm3s−1. The detailed analysis suggests that the fraction of total excitons that decay via long decay channel decreases with increasing exciton density for 2H–MoSe2, in contrast to 1T/2H–MoSe2 where the fraction of excitons decaying via long decay channel remains constant. [ABSTRACT FROM AUTHOR]

γ-GeSe has recently emerged as a promising material for electronics and optoelectronics due to its unique band structure and excellent electrical properties. However, controllable growth of γ-GeSe remains a significant challenge. In this work, the controllable growth of γ-GeSe microflakes (MFs) on a mica substrate was reported by vapor phase deposition via a rapid cooling strategy. The screw dislocation-driven growth behavior is confirmed based on systematic characterizations. Our experimental results demonstrate that the stress induced during the rapid cooling process is critical for the controllable synthesis of γ-GeSe MFs and corresponding growth mechanism was proposed. Our work provides a new experimental strategy for the controlled growth of γ-GeSe MFs, which is beneficial for constructing GeSe-based nanoelectronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Quaternary III–V semiconductors are one of the most promising material classes in optoelectronics. The bandgap and its character, direct or indirect, are the most important fundamental properties determining the performance and characteristics of optoelectronic devices. Experimental approaches screening a large range of possible combinations of III- and V-elements with variations in composition and strain are impractical for every target application. We present a combination of accurate first-principles calculations and machine learning based approaches to predict the properties of the bandgap for quaternary III–V semiconductors. By learning bandgap magnitudes and their nature at density functional theory accuracy based solely on the composition and strain features of the materials as an input, we develop a computationally efficient yet highly accurate machine learning approach that can be applied to a large number of compositions and strain values. This allows for a computationally efficient prediction of a vast range of materials under different strains, offering the possibility of virtual screening of multinary III–V materials for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Self-powered photodetectors (PDs) with distinguishable wavelength detection have great application potential in intelligent optoelectronics. However, slow response speed, low responsivity, and signal interference prevent its development and applications. Here, an asymmetric bipolar p-NiO/n-ZnO/p-Si heterojunction is designed as a wavelength-distinguishable PD by using two tandem p–n junctions to reduce the wavelength interference and effectively separate photo-generated carriers. Bidirectional transient photocurrents are achieved in the external circuit for ultraviolet and visible detection by smartly using the pyro-phototronic effect induced by the variations of spontaneous polarization and interface-induced polarization within the p–n–p junction. The transient peak-to-peak current are thus significantly improved by 2310% for 325 nm lasing and by 5950% for 442 nm lasing. This approach can be used to realize wavelength-distinguishable detection through flexibly selecting materials and using the pyro-phototronic effect. The designed PD might have potential applications in the fields of environmental detection, smart imaging, and intelligent optoelectronics. [ABSTRACT FROM AUTHOR]

Phyllosilicate minerals are an emerging class of naturally occurring layered insulators with large bandgap energy that have gained attention from the scientific community. This class of lamellar materials has been recently explored at the ultrathin two-dimensional level due to their specific mechanical, electrical, magnetic, and optoelectronic properties, which are crucial for engineering novel devices (including heterostructures). Due to these properties, phyllosilicate minerals can be considered promising low-cost nanomaterials for future applications. In this Perspective article, we will present relevant features of these materials for their use in potential 2D-based electronic and optoelectronic applications, also discussing some of the major challenges in working with them. [ABSTRACT FROM AUTHOR]

Solution-processed all-inorganic CsPbBr3 perovskite thin films show great promise for green lasers owing to their unique optoelectronic properties and processability. However, the amplified spontaneous emission (ASE) of CsPbBr3 films with poor heat dissipation still experiences instability due to severe heating effects under high optical pump densities. Here we demonstrate CsPbBr3:GO films with excellent photostability and ASE properties under ambient conditions by incorporating graphene oxide (GO) as an additive. As the amount of GO increases, the photostability of the perovskite film is improved and the ASE threshold is decreased, while the film surface remains smooth and compact. Moreover, a low threshold of ASE is sustained even after annealing the composite films at 130 °C for 24 hours. These results suggest that the synthesis of CsPbBr3:GO will open new avenues for controlling the optical properties of perovskite films and advancing the development of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Experimentally achieving the first‐ever electric field periodic poling of single crystal barium titanate oxide (BTO, or BaTiO3) thin film on‐insulator is reported. Owing to the outstanding optical nonlinearities of BTO, this result is a key step toward achieving quasi‐phase‐matching (QPM). First, the BTO thin film is grown on a dysprosium scandate substrate using pulsed laser deposition with a thin layer of strontium ruthenate later serving as the bottom electrode for poling. The characterization of the BTO thin film using x‐ray diffraction (XRD) and piezo‐response force microscopy to demonstrate single crystal, single domain growth of the film that enables the desired periodic poling, are presented. To investigate the poling quality, both non‐destructive piezo force response microscopy and destructive etching‐assisted scanning electron microscopy (SEM) are applied, and it is shown that high quality, uniform, and intransient poling with 50% duty cycle and periods ranging from 2 µm to 10 µm is achieved. The successful realization of periodic poling in BTO thin film unlocks the potential for highly efficient nonlinear processes under QPM that seemed far‐fetched with prior polycrystalline BTO thin films which predominantly relied on efficiency‐limited random or non‐phase matching conditions and is a key step toward integration of BTO photonic devices. [ABSTRACT FROM AUTHOR]

Lattice deformation via substrate‐driven mechanical straining of 2D materials can profoundly modulate their bandgap by altering the electronic band structure. However, such bandgap modulation is typically short‐lived and weak due to substrate slippage, which restores lattice symmetry and limits strain transfer. Here, it is shown that a non‐volatile thermomechanical strain induced during hot‐press synthesis results in giant modulation of the inherent bandgap in quasi‐2D tellurium nanoflakes (TeNFs). By leveraging the thermal expansion coefficient (TEC) mismatch and maintaining a pressure‐enforced non‐slip condition between TeNFs and the substrate, a non‐volatile and anisotropic compressive strain is attained with ε = −4.01% along zigzag lattice orientation and average biaxial strain of −3.46%. This results in a massive permanent bandgap modulation of 2.3 eV at a rate S (ΔEg) of up to 815 meV/% (TeNF/ITO), exceeding the highest reported values by 200%. Furthermore, TeNFs display long‐term strain retention and exhibit robust band‐to‐band blue photoemission featuring an intrinsic quantum efficiency of 80%. The results show that non‐volatile thermomechanical straining is an efficient substrate‐based bandgap modulation technique scalable to other 2D semiconductors and van der Waals materials for on‐demand nano‐optoelectronic properties. [ABSTRACT FROM AUTHOR]

Due to significant response contradictions, unidirectional carrier transmission of typical semiconductor p‐n junctions limits integrated sensors and artificial synapses in a monolithic device. In this work, a bipolar p‐n junction designed by employing the hydrogel/p‐GaN local contact interface with p‐GaN/(In,Ga)N heterojunction, demonstrating the bidirectional photocurrent and sensor/artificial synapse dual‐mode device successfully. After modifying Au nanoparticles, the negative (positive) photocurrent is increased by 900% (300%) under 365 nm (520 nm) light to achieve a more balanced bipolar carrier dynamic. Such a regulation of photocurrent is found to be attributed to the promotion of hydrogen evolution reaction (HER) at the hydrogel/Au/p‐GaN interface. Thus, the device achieves the ultrahigh paired‐pulse facilitation (PPF) index of 243% under self‐powered condition. Moreover, the implementation of plasticity from short‐term to long‐term demonstrates its adaptability in neural morphology visual recognition. Beyond independent working mode, the function of five classic logic gates is achieved under three‐terminal operation. Finally, an encrypted wireless communication system using dual‐channel light signals demonstrates the extensive application potential of the monolithic device. Therefore, this work presents a viable construction blueprint to meet the demands of next‐generation all‐in‐one optoelectronics for intricate application scenarios. [ABSTRACT FROM AUTHOR]

This work presents a study of piezoelectric zinc oxide (ZnO) thin films deposited by a novel post‐reactive sputtering method. The process utilizes a rotating drum with DC magnetron sputtering deposition onto substrates with subsequent DC plasma‐assisted oxidation of the deposited metal to metal oxide. The paper analyzes the influence of plasmaassisted magnetron sputtering (PA‐MS) deposition parameters (O2 plasma source power, O2 flow, and Ar flow) on the morphological, structural, optical, and piezoelectric properties of ZnO thin films. Design of experiments has been utilized to evaluate the role of these parameters on the growth rate (rg) and the properties of resulting films. Results indicate a predominant influence of the plasma power on the rg over other parameters. Among the eight tested samples, three of them show high crystal quality with high intensity (0001) diffraction peak, characteristic of the wurtzite crystalline structure of ZnO, and one of them exhibits piezoelectric coefficient values of ≈11pC N−1. That sample corresponding to a ZnO film deposited at the lowest rg of 0.075 nm s−1, confirmed the key role of the deposition parameters on the piezoelectric response of films, and demonstrated PA‐MS as a promising technique to produce high‐quality piezoelectric thin films. [ABSTRACT FROM AUTHOR]

When semiconductor crystals are made into the form of thin sheets, i.e., nanomembranes, their properties and behaviors may be remarkably different from their bulk counterparts. A plethora of fascinating science and important applications arise consequently, some of which are investigated in recent years, and there are still a lot more to be discovered in the future. Nanomembranes (NMs) provide a good platform for strain engineering and offer tremendous research opportunities in photonics and optoelectronics applications. Strain alters energy band line up of a material furthermore influencing its carrier mobility which impacts a wide range of applications. In this article, the strain‐engineered NMs are reviewed using semiconductor materials as a model system for photonics and optoelectronics applications. While many fundamental aspects of NMs are discussed and outlined different methods for strain engineering of NM, the use of semiconductor NMs for photonics and optoelectronics applications is the locus of the present review article. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have excellent electronic and optical properties, suggesting absolute advantages in nanodevices. In this work, a new two-dimensional material with a puckered structure, a C2B6 monolayer, is proposed. The material presents dynamic and thermal stability calculated by first-principle simulations. Interestingly, the C2B6 monolayer possesses semiconductor behavior with an ultra-narrow bandgap of approximately 0.671 eV by HSE06 functional. Meanwhile, the hole in the C2B6 monolayer shows ultrahigh mobility at approximately 6,342 cm2⋅V−1⋅s−1 in decent transport directions, which is larger than traditional transition metal dichalcogenides materials. More importantly, the pronounced anisotropy of mobility of the electrons and holes can separate the photogenerated charges, suggesting the applications for photocatalytic, photovoltaic and optical and cold chain electronic devices. Then, the novel properties of the light absorption characteristic are obtained, and the anisotropic photocurrent implies the C2B6 monolayer can be used as a potential photoelectric device. Our results provide theoretical guidance for the design and application of two-dimensional materials. [ABSTRACT FROM AUTHOR]

Organic optoelectronics have attracted widespread interdisciplinary research interest but lags far behind in the application in marine environmental detection. The organic photoelectrochemical transistor (OPECT) shows promise as a powerful tool for comprehensive monitoring and early warning of marine conditions, which can be further enhanced by the valuable signal amplification strategy of nanozyme‐mediated catalytic precipitation. Herein, OPECT technology is integrated with nanozyme‐mediated catalytic precipitation for the first time, establishing an ultrasensitive detection platform for okadaic acid (OA). Specifically, MXene@MnIn2S4 (MXMnIS) hybrid composed of Schottky‐junction is synthesized via a hydrothermal method, which can efficiently modulate the device with high current gain. Linking with a sandwich immunoassay, the Ru‐C3N4 nanozyme with peroxidase‐mimicking activity can catalyze the oxidation of 4‐chloro‐1‐naphthol (4‐CN) to form an insoluble precipitate on the electrode surface, resulting in a decrease in the photocurrent and altering the transistor response. Importantly, the proposed OPECT biosensor presented an excellent sensitivity and a low detection limit (32.5 pM), fully satisfying the fundamental requirements for the quantitative detection of intracellular and extracellular OA in the practical culture media of Prorocentrum lima at different growth stages. This OPECT platform based on the nanozyme‐mediated quenching effect is significant for effectively monitoring the safety of the marine ecological environment and food safety. [ABSTRACT FROM AUTHOR]

Due to the outstanding physical properties and the integrated characteristics, such as the gapless band structure, high state density, high conductivity, dangling‐bond‐free surface, and tunable Fermi level, two‐dimensional layered topological semimetals (2D LTSMs) exhibit a promising application prospect for including electrode contact and terahertz detection. Despite the surging in attention, a comprehensive strategy is still crucial to meet the necessary conditions for the practical application of 2D LTSMs. According to the fermion types and the band structures, 2D LTSMs can be divided into Dirac semimetals, Weyl semimetals, and nodal‐line semimetals. This review comprehensively encapsulates the intrinsic properties, typical synthesis methods, and applications in electronics and optoelectronics about these 2D LTSMs. To establish the fundamental theory, typical crystal structures, and physical properties of different 2D LTSMs are summarized at first. The effective synthesis strategies including exfoliation, molecular beam epitaxy, and vapor deposition are analyzed systematically. Finally, the article emphasizes the exploration of applications, significant challenges, and promising development directions of 2D LTSMs, which will drive 2D LTSMs to become the promisingly leading technology for next‐generation electronic and optoelectronic systems. [ABSTRACT FROM AUTHOR]

Smart persistent organic room‐temperature phosphorescence (RTP) materials, capable of responding to microenvironmental changes, are critically important in various optoelectronic applications. However, conventional persistent RTP materials usually have not stretchability and flexibility, limiting some practical applications. This study reports a facile and one‐pot photo‐initiated copolymerization method to prepare photoactivated persistent RTP polymers with multicolored afterglow, excellent stretchability, self‐healable and recyclable properties. Impressively, the polymers can be stretched up to 500% without significant loss in RTP intensity and lifetime, and they possess a self‐healing ability with a healing efficiency of 69.6%. Utilizing these photoactivated and stretchable persistent RTP polymers, dual encryption can be achieved under UV irradiation and stretching conditions, thereby enhancing the security levels of the stored confidential information. Overall, this study represents the first example of self‐healable and recyclable stimuli‐responsive RTP materials, demonstrating their bright future for the flexible and wearable optoelectronics. [ABSTRACT FROM AUTHOR]

Interband Cascade Lasers (ICL) have matured into a versatile technological platform in the mid‐infrared spectral domain. To broaden their applicability even further, ongoing research pursues the emission of ultrashort pulses. The most promising approach is passive mode‐locking with a fast saturable absorber. However, despite vast attempts no passive mode‐locked ICL has been demonstrated up to date. In this study, pump‐probe measurements are conducted on the ICL gain, demonstrating that ≈$\approx$60–70% of its dynamic behavior is characterized by a rapid recovery time of 2 ps. The findings explain why passive mode‐locking of ICLs has not succeeded so far, shedding a new light on ICL dynamics as strategies are proposed to overcome the current limitations. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are becoming essential materials for future scientific and real-world applications, owing to their interesting and distinct optical and electrical properties compared to their bulk-state counterparts. The ability to tune the bandgap of QDs based on size and composition—a key characteristic—opens up new possibilities for enhancing the performance of various optoelectronic devices. These advances could extend to cutting-edge applications such as ultrawide-band or dual-band photodetectors (PDs), optoelectronic logic gates, neuromorphic devices, and security functions. This paper revisits the recent progress in QD-embedded optoelectronic applications, focusing on bandgap tunability. The current limitations and challenges in advancing and realizing QD-based optoelectronic devices are also discussed. [ABSTRACT FROM AUTHOR]

Purpose: The study highlights our findings, including the confirmation of phase stability through XRD analysis, the characterization of optical properties revealing high absorption and conductivity and the analysis of mechanical stability through elastic constants. Additionally, we present detailed results on the band gap, EELS analysis and the suitability of SrZrO3 perovskite oxides for next-generation optoelectronic devices. Design/methodology/approach: Cubic SrZrO3 perovskite oxides were designed within the framework of density functional theory (DFT) via the CASTEP code under varying stress conditions (0–100 GPa), aiming to explore the key properties for diverse applications. The phase stability was confirmed by XRD analysis. From 0 to 40 GPa, there is an increase in the band gap from 3.330 to 3.615 eV, while it narrows from 3.493 to 3.155 eV beyond 60 GPa. The optical characteristics revealed high absorption, superior conductivity and a lower loss function. Significantly, the elastic constants (C11, C12 and C44) satisfy the Born-stability criterion, ensuring the mechanical stability of the compound. Additionally, the Poisson's ratio, Pugh ratio (B/G), Frantsevich ratio, Cauchy pressure (PC) and anisotropy factor ensured both ductile and anisotropic characteristics. Higher values of Young's modulus and shear modulus signify a superior ability to withstand longitudinal stresses. In the EELS analysis, distinctive energy-loss peaks resulting from absorption and emission correlated with diverse electronic transitions and energy levels associated with Sr, Zr and O atoms are used to probe the precise exploration of the electronic and optical characteristics of materials with a high degree of accuracy. Based on these findings, the designed SrZrO3 perovskite oxides are particularly suitable for applications in various optoelectronic devices. Findings: CASTEP codes were utilized to design the cubic SrZrO3 perovskite under varying stress conditions ranging from 0 to 100 GPa. The phase stability was confirmed through XRD analysis. A distinctive trend in the band gap was observed: an increase from 3.330 eV to 3.615 eV as the stress increased from 0 to 40 GPa and a decrease from 3.493 to 3.155 above 60 GPa. A higher absorption and conductivity and a lower loss function were found for the optical properties. The mechanical stability was ensured by elastic constants (C11, C12, and C44) satisfying the Born-stability criteria. Additionally, the Poisson's ratio, Pugh's ratio (B/G), Frantsevich ratio, Cauchy pressure (PC) and anisotropy factor were used to verify the ductility and anisotropy of the materials. Higher values of Young's modulus and shear modulus indicate a superior ability to withstand longitudinal stresses. EELS analysis revealed distinctive energy-loss peaks associated with Sr, Zr and O atoms, enabling precise exploration of the electronic and optical characteristics with a high degree of accuracy. As expected, the designed SrZrO3 perovskite oxides exhibit favorable properties, making them particularly suitable for next-generation optoelectronic devices. Originality/value: In this study, we utilized DFT within the CASTEP code framework to investigate the properties of cubic SrZrO3 perovskite oxides under varying stress conditions ranging from 0 to 100 GPa. Our research aimed to explore the key properties of SrZrO3 for diverse applications, particularly in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Various quartz microlenses were fabricated in two stages with two lasers. A fiber laser at 1.06 µm was employed for the laser ablation, while a CO2 laser at 10.6 µm was used for direct laser writing (DLW). The experimental data demonstrate the formation of spherical, cylindrical microlenses and microlens array (MLA) with an optimum numerical aperture (NA) of 0.55. Theoretical calculations and simulation were conducted to estimate the temperature at the quartz surface during ablation and simulation of the reshaping. A temperature of 2500 K is achieved in the ablation, and 2015 K was established during the reshaping. The ablation depth is 280 µm, the diameter is 150 µm, and the heat affected zone (HAZ) is approximately 1345 µm after 1 s. Due to the controllable laser micromachining, optoelectronics and biological imaging are viable applications for MLAs. [ABSTRACT FROM AUTHOR]

Optical interconnects, leveraging surface plasmon modes, are revolutionizing high-performance computing and AI, overcoming the limitations of electrical interconnects in speed, energy efficiency, and miniaturization. These nanoscale photonic circuits integrate on-chip light manipulation and signal conversion, marking significant advancements in optoelectronics and data processing efficiency. Here, we present a novel plasmonic interconnect circuit, by introducing refractive index matching layer, the device supports both pure SPP and different hybrid modes, allowing selective excitation and transmission based on light wavelength and polarization, followed by photocurrent conversion. We optimized the coupling gratings to fine-tune transmission modes around specific near-infrared wavelengths for effective electrical detection. Simulation results align with experimental data, confirming the device's ability to detect complex optical modes. This advancement broadens the applications of plasmonic interconnects in high-speed, compact optoelectronic and sensor technologies, enabling more versatile nanoscale optical signal processing and transmission. [ABSTRACT FROM AUTHOR]

Band structure and gain in a Ge/Ge1-xSnx/Ge quantum well are described theoretically using a 14-band k.p model. It has been shown that the quantum well width and the α-Sn concentration considerably modify the conduction and valence subband structure, and, as a result, the optical gain changes with the insertion of a very small concentration of α-Sn. In particular, we have determined the necessary injection carrier density Nj and the critical α-Sn concentration for elevated high gain lasing. It is found that for Nj = 1.5 × 1018 cm−3, we achieved a maximum peak gain for α-Sn concentration of the order 0.155. We can predict that Ge/Ge1-xSnx/Ge QWs should be manufactured with an α-Sn concentration less than 0.155 in devices for optoelectronics applications such as telecommunication and light emitting laser diodes. [ABSTRACT FROM AUTHOR]

Halide perovskites have attracted increasingly attention as "rising star" materials for advanced photonics and optoelectronics. Construction micro‐/nano‐architecture of perovskites will provide a good platform to investigate and optimize the fundamental photon–matter–structure interaction. It will also improve the properties, pixelate and miniaturize the integration of versatile optoelectronic devices for emerging applications. In this regard, femtosecond (fs) laser processing technique has been widely used to fabricate micro‐/nano‐architecture with high spatial resolution, limitless flexibility, and unrestricted three‐dimensional structuring capability at a large‐scale, low‐cost way. Concurrently, it is reported that the high refractive index, low thermal conductivity and ultrafast thermalization rate of perovskites are beneficial for the processing by fs laser into micro‐/nano‐architecture without the degradation of their optoelectronic properties. This review systematically summarizes the interaction of fs laser with perovskites, including the mechanisms, and phenomena. Besides the traditional optoelectronics and applications of halide perovskites, the novel properties and applications from optical structures generated by fs laser processing of perovskites are also discussed. The challenges and outlooks for fs laser processed perovskite materials and devices are highlighted. This review will promote the relevant fundamental research on light–matter–structure interaction, and facilitate the integration of perovskite micro‐/nano‐architecture‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Moiré superlattices based on twisted transition metal dichalcogenide (TMD) heterostructures have recently emerged as a promising platform for probing novel and distinctive electronic phenomena in two-dimensional (2D) materials. By stacking TMD monolayers with a small twist angle, these superlattices create a periodic modulation of the electronic density of states, leading to the formation of mini bands. These mini bands can exhibit intriguing properties such as flat bands, correlated electron behavior, and unconventional superconductivity. This review provides a comprehensive overview of recent progress in Moiré superlattices formed from twisted TMD heterostructures. It covers the theoretical principles and experimental techniques for creating and studying these superlattices, and explores their potential applications in optoelectronics, quantum computing, and energy harvesting. The review also addresses key challenges, such as improving the scalability and reproducibility of the fabrication process, emphasizing the exciting opportunities and ongoing hurdles in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

Temperature dependency of band gap in CuO nano thin films has been investigated by virtue of transmission experiments at different temperatures. Structural and morphological characterization were achieved using X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. Analysis on the XRD diffractogram revealed the presence of monoclinic structure for the CuO. Average crystallite size was determined as 17.8 nm. Absorption characteristics in between 10 and 300 K were presented in the wavelength range of 360–1100 nm. The band gap of the CuO was found to be ~ 2.17 eV at 300 K using Tauc and spectral derivative methods. This value increased to ~ 2.24 eV at 10 K. Both methods showed that the band gap extended with decreasing temperature. Temperature dependency of the band gap was studied using Varshni relation. The band gap at absolute temperature, variation of the band gap with temperature and Debye temperature were calculated as 2.242 ± 0.002 eV, − 5.4 ± 0.2 × 10−4 eV/K and 394 ± 95 K, respectively. [ABSTRACT FROM AUTHOR]

In the current study, it is aimed to scrutinize the physical properties of LiBeX (X = Sb, Bi) compounds in detail. Density‐functional‐theory‐based WIEN2k and the Vienna Ab initio Simulation Package, employing the generalized gradient approximation of Perdew–Burke–Ernzerhof, Wu–Cohen, and Tran–Blaha‐modified Becke–Johnson (TB‐mBJ) exchange‐correlation schemes, are utilized to better validate the outcomes. The compounds exhibit energetic, lattice dynamic, and mechanical stability. Electronic structure calculations using the TB‐mBJ functional reveal indirect bandgaps of 1.007 eV for LiBeSb and 0.789 eV for LiBeBi compounds, respectively. The partial charge distribution in the highest occupied molecular orbital and the lowest unoccupied molecular orbital discloses maximum charge localization around the X site. The examination of the crystal orbital Hamilton population reveals the strongest BeX bonding interactions among the bonding pairs. The physio‐mechanical properties indicate brittle and mechanically anisotropic behavior of both compounds, with covalent bonding characteristics. The comparative analysis suggests that the TB‐mBJ potential is suitable for bandgap calculations due to its close alignment with experimental results. Additionally, the optimized results for these compounds indicate their potential for use in optoelectronic devices, such as visible to ultraviolet sensors and photovoltaics. The determined properties are consistent with previous theoretical findings. [ABSTRACT FROM AUTHOR]

Recently, giant quantum dots (g‐QDs) with a core/interface graded alloy shell/shell structure have shown promise in reducing photoluminescence (PL) intermittency and improving photostability. However, this approach has been mainly demonstrated with red and green emitting g‐QDs but the blue‐emitting graded alloy QDs has remained less explored. To tackle this challenge, a composition gradient method is employed to create three blue‐emitting CdZnS/CdxZn1–xS/ZnS core/interface graded alloy shell/shell (C/A/S) quantum dots (QDs) with different diameters. The sample with the largest diameter (gQD‐3) exhibits superior optical characteristics, with a photoluminescence quantum yield (PLQY) of approximately 62% and around 80% ON/radiative events at the single‐particle level. Conversely, the smallest diameter (gQD‐1) sample shows lower PLQY and only 30% radiative events with longer OFF/nonradiative events. Probability distribution analysis of PL trajectories, fitted with a truncated power law, reveals a significantly higher carrier de‐trapping rate in gQD‐3 compared to gQD‐1, attributed to its proximity to band edge trap states. Additionally, the largest diameter sample retains remarkable optical performance during 48 h of continuous UV irradiation in colloidal suspension and single‐particle levels. These findings show optimized core/shell structures, gradual alloy interfaces, and outer shell coatings can stabilize blue‐emitting quantum dots, advancing next‐gen optoelectronics. [ABSTRACT FROM AUTHOR]

Carbazole derivatives are vital in medicinal and materials chemistry, yet accessing diverse substitutions remains challenging. Here, we introduce a regioselective approach for C1 and C8 alkynylation of carbazoles via palladium‐catalyzed C−H activation. This method provides a direct route to mono‐ and di‐alkynylated derivatives, addressing the scarcity of alkynylated carbazole‐based materials. Our study broadens the synthetic toolbox for carbazole functionalization, offering potential applications in optoelectronics, bio‐imaging, and beyond, while contributing to developing sustainable C−H activation methodologies. [ABSTRACT FROM AUTHOR]

We studied the RbV3Sb5 kagome compound's structural, mechanical, thermal, and optoelectronic properties. Mulliken and Hirshfeld population analysis found ionic and covalent connections in RbV3Sb5. The Born stability criterion shows that pure RbV3Sb5 is mechanically stable. The precise measurement of 3.96 indicates that our sample has higher machinability at 20 GPa. Low anticipated hardness of RbV3Sb5 suggests it can be used as a soft solid lubricant. Hardness ratings rise with pressure, however there are exceptions. Pressure causes large nonmonotonic changes in RbV3Sb5′s anisotropic characteristics. A comparable 20 GPa Zener anisotropic value, RbV3Sb5 has the highest. The structure's projected Debye temperature at 0 GPa is 284.39 K, indicating softness. Dispersion curves with negative frequencies suggest ground state structural dynamical instability. The structure has no negative‐energy phonon branches under 10 GPa stress. From band structure and density of state analysis, the structure behaves metallically under hydrostatic pressure. Also, the structure has maximal ultra‐violet conductivity and absorption. The absorption coefficient, conductivity, and loss function plots show uniform patterns at all pressures. As pressure rises, these graphs’ peaks blue shift. [ABSTRACT FROM AUTHOR]

2D materials, owing to their nearly atomic thickness, have emerged as promising candidates across a broad spectrum of next‐generation devices and systems. In the post‐graphene era, molybdenum‐based dichalcogenides (MoX2, where X = S, Se, Te), possessing a graphene‐like structure, represent one of the most promising subsets among 2D transition metal dichalcogenides (TMDs) due to their extensively researched and distinctive electronic, optical, and mechanical properties. Further with their distinct properties of different phases (2H, 1T) make it attractive for both fundamental and applied research. It finds diverse applications, spanning from optoelectronics to catalysis and sensor development. In this review article, the unique crystal structural properties of MoX2 are highlighted and their different synthesis methods, incorporating recent advancements in synthesis approaches discussed. Subsequently the recent development of MoX2 nanocomposite based on carbon, metal, metal oxide and various polymer discussed. Finally, the key challenges impeding the advancement of sensing applications and propose avenues for future development, drawing upon the current progress in 2D MoX2 and their nanocomposites also find mention in this review. [ABSTRACT FROM AUTHOR]

Non-fullerene acceptor (NFA) molecules attracted huge attention from the photovoltaic community for their potential use in organic solar cells (OSCs). Herein, we designed a series of NFA materials (AR1–AR9) for OSCs by altering end-capped moieties. We employed various advanced density functional theory (DFT) and time-dependent (TD-DFT) approaches to characterize this designed AR1–AR9 series. Compared to the synthetic reference molecule (R), designed molecules AR1–AR9 revealed a smaller bandgap (1.85 eV), and improved absorption spectra (λmax 741 nm) in comparison to R (λmax 668 nm), indicating the better potential for the tailored molecules. Furthermore, the designed series (AR1–AR9) shows lower reorganization energy values (for holes and electrons) and lower binding energies (0.323 eV), whereas, improved charge mobilities, showing them better candidates for OSCs. Moreover, frontier molecular orbitals (FMO), open-circuit voltages (Voc) and improved charge-transfer characteristics have also been investigated. These findings revealed that all developed NFAs exhibited a wide range of exciton dissociation constants and enhanced absorption efficiency with a relatively lower LUMO energy level. Therefore, we believe that these materials will be beneficial in boosting the power conversion efficiency (PCE) of OSC devices by improving their optoelectronic and photophysical properties. [ABSTRACT FROM AUTHOR]

This study reveals a local strain‐dependent etching behavior that enables the formation of distinguished etching patterns in differently strained chemical vapor deposited (CVD) 2D molybdenum disulfide (MoS2) monolayers. It is demonstrated that when the local tensile strain of CVD 2D MoS2 is as uniformly low as ɛ ≈ 0.33% or less, the oxidative etching pattern possesses conventional triangular etching pits (TEPs), while when the local tensile strain is as uniformly high as ɛ ≈ 0.55% or larger, the oxidative etching pattern consist of uniformly oriented hexagonal etching channels (HECs). More interestingly, when the CVD 2D MoS2 monolayer has heterogenous strain distribution from ɛ ≈ 0.55% (center region) to ɛ ≈ 0.33% (perimeter region), the oxidative etching pattern comprise of non‐uniformly hexagonal‐mixed‐parallel etching channels (HPECs). The further characterization and analysis reveal the formation mechanism of such strain‐dependent etching patterns is built on the local strain‐related fractures propagation under oxidative etching, as well as the anisotropy fractures‐based oxidative etching kinetics. This study may enhance the understanding of the relationship between etching and growth features of 2D TMDs, and paves the way to etching‐nanostructured (or defect) engineering of 2D TMDs and other 2D materials for potential applications in electrocatalysis and optoelectronics. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) of chiral luminescent materials has gained increasing attention because of their significant applications in 3D displays, chiral optoelectronics, anti‐counterfeiting, and encryption. A strongly emissive chiral dye BAcT is synthesized using (R)‐BINOL as the chiral source and a tetraphenylethene group as the fluorophore. Upon the addition of BAcT to the nematic liquid crystal, a left‐handed cholesteric structure is induced. Different concentrations of R/S5011 as chiral co‐dopants are added to prepare a series of structurally colored cholesteric liquid crystal polymer network (CLCN) films. CPL bands are detected for these green emissive CLCN films, and relatively high |glum| values (up to 0.48) are obtained. Furthermore, a fluorescent PMMA‐BAcT layer is prepared by embedding the dye in the PMMA matrix and stacked with a CLCN layer to construct a composite film. Because of the chiral filtering effect of the CLCN film, a high |glum| value up to 1.41 is successfully achieved. Colorful CLCN patterns are prepared, and clear pictures are observed in both reflective and fluorescent modes, contributing to optical anti‐counterfeiting with enhanced security. This work not only provides a deeper understanding of CPL, but also establishes a practical strategy to prepare colorful CLCN patterns for anti‐counterfeiting using inkjet printing technology. [ABSTRACT FROM AUTHOR]

This paper presents an 8 × 8 channel optoelectronic readout array (ORA) realized in the TSMC 180 nm 1P6M RF CMOS process for the applications of short-range light detection and ranging (LiDAR) sensors. We propose several circuit techniques in this work, including an amplitude-to-voltage (A2V) converter that reduces the notorious walk errors by intensity compensation and a time-to-voltage (T2V) converter that acquires the linear slope of the output signals by exploiting a charging circuit, thus extending the input dynamic range significantly from 5 μApp to 1.1 mApp, i.e., 46.8 dB. These results correspond to the maximum detection range of 8.2 m via the action of the A2V converter and the minimum detection range of 56 cm with the aid of the proposed T2V converter. Optical measurements utilizing an 850 nm laser diode confirm that the proposed 8 × 8 ORA with 64 on-chip avalanche photodiodes (APDs) can successfully recover the narrow 5 ns light pulses even at the shortest distance of 56 cm. Hence, this work provides a potential CMOS solution for low-cost, low-power, short-range LiDAR sensors. [ABSTRACT FROM AUTHOR]

This study addresses the challenge of modeling temperature-dependent photoluminescence (PL) in CdS colloidal quantum dots (QD), where PL properties fluctuate with temperature, complicating traditional modeling approaches. The objective is to develop a predictive model capable of accurately capturing these variations using Long Short-Term Memory (LSTM) networks, which are well suited for managing temporal dependencies in time-series data. The methodology involved training the LSTM model on experimental time-series data of PL intensity and temperature. Through numerical simulation, the model's performance was assessed. Results demonstrated that the LSTM-based model effectively predicted PL trends under different temperature conditions. This approach could be applied in optoelectronics and quantum dot-based sensors for enhanced forecasting capabilities. [ABSTRACT FROM AUTHOR]

Germanane (GeH) and silicane (SiH), members of the Xanes family, have garnered significant attention as 2D materials due to their diverse properties, which hold promise for applications in electronics, optoelectronics, energy storage, and sensing. Typically, highly concentrated hydrochloric acid (HCl) or hydrofluoric acid (HF) is employed in the synthesis of these Xanes, but both routes are problematic due to slow kinetics and safety concerns, respectively. Here for the first time, a faster and safer method is demonstrated for Xanes synthesis that harnesses the generation of HF “in situ” using a solution of HCl and lithium fluoride (LiF) salt, overcoming the key challenges of the conventional methods. A variety of characterization techniques to establish a baseline is utilized for both Xanes and to provide a holistic knowledge regarding this method, the possible consequences of this approach, and the possibility of applying it to other layered Zintl phases. The novel synthesis protocol results in high‐quality GeH and SiH with bandgaps (Eg) of 1.75 and 2.47 eV respectively, highlighting their potential suitability for integration into semiconductor applications. [ABSTRACT FROM AUTHOR]

This research presents a comprehensive study of a Schottky diode fabricated using a gold wafer and a bilayer molybdenum disulfide ( MoS 2 ) film. Through detailed simulations, we investigated the electric field distribution, potential profile, carrier concentration, and current–voltage characteristics of the device. Our findings confirm the successful formation of a Schottky barrier at the Au/ MoS 2 interface, characterized by a distinct nonlinear I–V relationship. Comparative analysis revealed that the Au/ MoS 2 diode significantly outperforms a traditional W/Si structure in terms of rectification performance. The Au/ MoS 2 diode exhibited a current density of 1.84 × 10 − 9 A/ cm 2 , substantially lower than the 3.62 × 10 − 5 A/ cm 2 in the W/Si diode. Furthermore, the simulated I–V curves of the Au/ MoS 2 diode closely resembled the ideal diode curve, with a Pearson correlation coefficient of approximately 0.9991, indicating an ideality factor near 1. A key factor contributing to the superior rectification performance of the Au/ MoS 2 diode is its higher Schottky barrier height of 0.9 eV compared to the 0.67 eV of W/Si. This increased barrier height is evident in the band diagram analysis, which further elucidates the underlying physics of Schottky barrier formation in the Au/ MoS 2 junction. This research provides insights into the electronic properties of Schottky contacts based on two-dimensional MoS 2 , particularly the relationship between electronic barriers, system dimensions, and current flow. The demonstration of high-ideality-factor Au/ MoS 2 diodes contributes to the design and optimization of future electronic and optoelectronic devices based on 2D materials. These findings have implications for advancements in semiconductor technology, potentially enabling the development of smaller, more efficient, and flexible devices. [ABSTRACT FROM AUTHOR]

Nanomaterials have superior electronic, optical, and mechanical properties making them highly suitable for a range of applications in optoelectronics, biomedical fields, and photonics. Nanomaterials‐based IR detectors are rapidly growing due to enhanced sensitivity, wide spectral range, and device miniaturization compared to commercial photodetectors. This review paper focuses on the significant role of nanomaterials in infrared detection, an area critical for enhancing night vision and health monitoring technologies. The latest advancements in IR photodetectors that employ various nanomaterials and their hybrids are discussed. The manuscript covers the operational mechanisms, device designing, performance optimization strategies, and material challenges. This review aims to provide a comprehensive overview of the current developments in nanomaterial‐based IR photodetectors and to identify key directions for future research and technological advancements. [ABSTRACT FROM AUTHOR]

Two-dimensional semiconductors have shown great potential for the development of advanced intelligent optoelectronic systems. Among them, two-dimensional perovskite oxides with compelling optoelectronic performance have been thriving in high-performance photodetection. However, harsh synthesis and defect chemistry severely limit their overall performance and further large-scale heterogeneous integration. Here, we report the wafer-scale integration of highly oriented nanosheets by introducing a charge-assisted oriented assembly film-formation process and confirm its universality and scalability. The shallow-trap dominance induced by structural optimization endows the device with a distinguished performance balance, including high photosensitivity close to that of single nanosheet units and fast response speed. An integrated ultra-flexible 256-pixel device demonstrates the versatility of material-to-substrate integration and conformal imaging functionality. Moreover, the device achieves efficient recognition of multidirectional motion trajectories with an accuracy of over 99.8%. Our work provides prescient insights into the large-area fabrication and utilization of 2D perovskite oxides in advanced optoelectronics. Deng et al. report a charge-assisted oriented assembly for wafer-scale film formation of 2D perovskite oxide nanosheets. An ultra-flexible 256-pixel photodetector array enables conformal imaging capability and achieves high-accuracy motion recognition with the convolutional neural network. [ABSTRACT FROM AUTHOR]

Optical emissions from two-dimensional transition metal dichalcogenides greatly differ from sample to sample due to their interactions with different substrates with variations in parameters such as the dielectric constant, absorption coefficient, growth conditions, strain, and defects. Often, the mechanisms of environmentally sensitive optical emission in 2D materials are lacking, and it is essential to perform the measurements on the same sample with different substrate backgrounds, which is a challenge. In this work, we explore photoluminescence engineering by comparing the optical properties of WS2 on SiO2, TiOx, and Pt by selectively creating different environments locally on the same sample. The PL-confocal map with good spatial resolution reveals that the emission of WS2 on TiOx and Pt is suppressed by charge transfer at the interface. While moving from WS2 on Pt toward WS2 on the TiOx region, a 3-fold enhancement in PL emission has been observed in agreement with a 20% increase in the trion-to-exciton ratio and calculated carrier densities. Further, the transient absorption spectroscopy shows faster exciton recombination in WS2/Pt (∼5.7 ps) and WS2/TiOx (∼7.2 ps) than WS2/SiO2 (∼48.5 ps), confirming the charge transfer in varied optical emission of the WS2 monolayer. Our method paves the way for using charge transfer and controlled carrier injection to design nanoantennas, optoelectronic devices, and quantum optical cavities in 2D materials. [ABSTRACT FROM AUTHOR]

Single‐photon detectors (SPDs) are crucial in applications ranging from space, biological imaging to quantum communication and information processing. The SPDs that operate at room temperature are of particular interest to broader application space as the energy overhead introduced by cryogenic cooling can be avoided. Although silicon‐based single photon avalanche diodes (SPADs) are well‐matured and operate at room temperature, the bandgap limitation restricts their operation at telecommunication wavelength (1550 nm) and beyond. InGaAs‐based SPADs, on the other hand, are sensitive to 1550 nm photons but suffer from relatively lower efficiency, high dark count rate, afterpulsing probability, and pose hazards to the environment from the fabrication process. In this work, the properties of nanomaterials that can be leveraged to address these challenges are demonstrated and a room‐temperature single‐photon detector capable of operating at 1550 nm is realized. This is achieved by coupling a low bandgap (≈ 350 meV) absorber (black phosphorus) to a sensitive van der Waals probe that is capable of detecting discrete electron fluctuation. The device is optimized for operation at 1550 nm and demonstrates an overall quantum efficiency of 21.4% (estimated as 42.8% for polarized light), and a minimum dark count of ≈ 720 Hz at room temperature. [ABSTRACT FROM AUTHOR]

The construction of miniaturized light-emitting diodes (LEDs) with high external quantum efficiency (EQE) at room temperature remains a challenge for on-chip optoelectronics. Here, we demonstrate microsized LEDs fabricated by a dry-transfer van der Waals (vdW) integration method using typical layered Ruddlesden-Popper perovskites (RPPs). A single-crystalline layered RPP nanoflake is used as the active layer and sandwiched between two few-layer graphene contacts, forming van der Waals LEDs (vdWLEDs). Strong electroluminescence (EL) emission with a low turn-on current density of ~20 pA μm-2 and high EQE exceeding 10% is observed at room temperature, which sets the benchmark for the EQE of vdWLEDs ever recorded. Such efficient EL emission is attributed to the inherent multiple quantum well structure and high photoluminescence quantum yield (~35%) of RPPs and a low charge injection barrier of ~0.10 eV facilitated by the Fowler-Nordheim tunneling mechanism. These findings promise a scalable pathway for accessing high-performance miniaturized light sources for on-chip optical optoelectronics. [ABSTRACT FROM AUTHOR]

Herein, niobium pentoxide (Nb2O5) nanosheets grown by the thermal evaporation technique under a vacuum pressure of 10− 5 mbar are treated as terahertz band filters. The amorphous thin layers of Nb2O5 exhibited high light transmittance and showed optical absorption within an energy band gap of 3.68 eV. The band gap contained wide-extended band tails with Urbach energy of 2.27 eV. As terahertz optical band filters, Nb2O5 nanosheets displayed a cutoff frequency of ~ 1.0 THz in the spectral range of 1.15–3.37 eV. Larger exciting light signals in the ultraviolet range increased the terahertz cutoff frequency from 1.2 THz to 170 THz as the light energy increased from 3.38 eV to 4.20 eV, respectively. Additionally, the fitting of the optical conductivity using the Drude-Lorentz model has shown that the optical conduction in Nb2O5 is associated with six optical oscillators. Two of these oscillators are dominant in the infrared range of light, three are active in the visible range, and one is sensitive to ultraviolet light radiation. The drift mobility of the charge carriers in the films varied in the ranges of 1.76–3.67 cm2/Vs. Electrical verification of the optical results was actualized through the design of Yb/p-Nb2O5/Ag band filters. This electrical device showed a negative capacitance effect and exhibited a cutoff frequency of 1.0 THz when a driving signal of frequency 0.597 GHz was imposed between the terminals of the device. These features prove the suitability of the terahertz band filters of Nb2O5 nanosheets for use as optical and electrical filters with an extremely wide range of tunability. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) offer tremendous advantages in the fields such as bioimaging, sensing, biomedicine, catalysis, information encryption, and optoelectronics. However, the inherent challenge is synthesizing CDs with a full-spectrum emission, as most CDs typically produce only blue or green emissions, which severely hinder further investigation into their fluorescence mechanism and restrict their broader applications in light-emitting diodes (LEDs). In this work, we reported a solvent-controlled strategy for the preparation of multicolor CDs with blue, yellow, and red emissions, using o-phenylenediamine (oPD) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) as precursors. The detailed characterizations proved that a solvent with a lower boiling point and lower solubility of precursors resulted in a higher degree of dehydration and carbonization process, thereby increasing carbon cores with sp2-conjugated domains and nitrogen doping and further reducing the bandgap energies, causing a significant redshift emission from blue to red. The underlying fluorescence mechanism of the prepared multicolor CDs was contributed to the surface state. Eventually, blue-, yellow-, and red-emitting CDs based on poly(vinyl alcohol) (PVA) films and colorful LEDs devices were fabricated by dispersing the as-synthesized CDs into a PVA solution. The proposed solvent-controlled strategy for multicolor CDs preparation will be helpful for fully utilizing the advantages of CDs and expanding their applications. [ABSTRACT FROM AUTHOR]

One of the major challenges in QLED research is improving the stability of the devices. In this study, we fabricated all inorganic quantum-dot light emitting diodes (QLEDs) using hafnium oxide (HfOx) as the hole transport layer (HTL), a material commonly used for insulator. Oxygen vacancies in HfOx create defect states below the Fermi level, providing a pathway for hole injection. The concentration of these oxygen vacancies can be controlled by the annealing temperature. We optimized the all-inorganic QLEDs with HfOx as the HTL by changing the annealing temperature. The optimized QLEDs with HfOx as the HTL showed a maximum luminance and current efficiency of 66,258 cd/m2 and 9.7 cd/A, respectively. The fabricated all-inorganic QLEDs exhibited remarkable stability, particularly when compared to devices using organic materials for the HTL. Under extended storage in ambient conditions, the all-inorganic device demonstrated a significantly enhanced operating lifetime (T50) of 5.5 h, which is 11 times longer than that of QLEDs using an organic HTL. These results indicate that the all-inorganic QLEDs structure, with ITO/MoO3/HfOx/QDs/ZnMgO/Al, exhibits superior stability compared to organic-inorganic hybrid QLEDs. [ABSTRACT FROM AUTHOR]