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This study investigates the synthesis of heavy-metal-free AgInS2 quantum dots (QDs) using a facile successive ionic layer adsorption and reaction (SILAR) method, exploring their application in quantum dot-sensitized solar cells (QDSSCs). The AgInS2 QDs were grown on mesoporous TiO2 via a two-stage SILAR process at room temperature. The optimization of Ag-S SILAR cycles (n) was performed to determine the ideal conditions, while the In-S SILAR cycles were held constant at seven cycles. X-ray diffraction (XRD) pattern analysis revealed an orthorhombic crystalline structure of the synthesized AgInS2 QDs. Analysis of the optical spectra revealed a reduction in the optical energy bandgap (Eg,op) of AgInS2 QDs from 2.00 eV to 1.92 eV and further to 1.78 eV as the value of n increased from 1 to 3. Employing AgInS2 QDs, a polysulfide electrolyte, and a CuS counter electrode, liquid-junction semiconductor QDSSCs were fabricated. Optimal conditions were achieved at n = 2, resulting in outstanding power conversion efficiency (PCE) of 3.57% (Jsc = 8.56 mA/cm2, Voc = 0.64 V, FF = 65.2%). Under reduced light intensity (0.25 sun), the PCE increased to 5.26%. The external quantum efficiency (EQE) spectrum of the best cells spanned 400−700 nm, maintaining a nearly constant EQE value of ~ 65% within the 400−600 nm range. Remarkably, the PCE achieved surpassed previously reported liquid-junction AgInS2 QDSSCs. These findings highlight the facile production of heavy-metal-free AgInS2 QDs through a room-temperature SILAR method and the tunable optical properties of AgInS2 QDs by controlling Ag-S SILAR cycles, revealing their potential as an efficient solar absorber. [ABSTRACT FROM AUTHOR]

This review provides an in-depth analysis of the latest non-toxic quantum dot (QD) synthesis strategies and their applications in optoelectronics and biomedical engineering. In addition, this review presents the development of synthetic approaches for non-heavy metal QDs that retain the desirable photophysical properties of their traditional counterparts while reducing their potential toxicity. We highlight the pivotal role of non-toxic QDs in advancing display technologies, focusing on their contribution to improving color purity and brightness in next-generation screens. In the biomedical field, applications of non-toxic QDs in bio-imaging, bio-sensing, and targeted drug delivery have been elaborated, emphasizing their enhanced biocompatibility and utility in precise diagnostics and therapeutics. The authors present insights and challenges underlining the transformative potential of non-toxic QDs for high-resolution display devices and advanced biomedical solutions to improve their functional attributes and safety for practical use. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are widely studied for their superior optical properties. However, maintaining their stability requires effective protection against heat and moisture. This research aims to enhance the stability of QDs by embedding them in cyclic olefin copolymer (COC). Our findings show that nanocomposites containing green- and red-emitting QDs in COC exhibited enhanced transparency and dispersion when compared to those using other common polymers, such as polydimethylsiloxane (PDMS) and poly(methyl methacrylate) (PMMA). Stability test under harsh conditions (85 °C and 85% relative humidity) confirmed the robustness of the QDs within the COC matrix compared to the PDMS and PMMA matrices. In addition, a white-light-emitting diode (LED) device was successfully fabricated by integrating a blend of green- and red-emitting QDs in COC-based nanocomposites atop a blue LED chip. This setup demonstrated potential for use in light-emitting devices that demand high luminous efficiency and transparency, even under extreme conditions. The study highlights the potential of COC as an alternative to traditional polymers, enhancing the performance and durability in display technologies. [ABSTRACT FROM AUTHOR]

The advent of quantum dots (QDs) enables us to reshape the incident light spectrum through absorption and re-emission. By exploiting the distinctive optical properties of QDs, a diverse array of optoelectronic devices that integrate QDs, including light-emitting diodes, solar cells, optical filters, and other applications, have gained widespread acceptance. Among promising applications for energy generation, luminescent solar concentrators (LSCs) exhibit remarkable potential, where QDs absorb incident solar light and re-emit it through QDs waveguides to edge-mounted solar cells. The substantial Stokes shift of QDs effectively mitigates addressed issues related to reabsorption, and the utilization of solution-processed QDs facilitates the development of low-cost LSCs. Consequently, considerable research efforts have been directed toward the development of QD-based LSCs, aiming to harness solar light more efficiently at reduced costs. This review systematically examines the potential of QD-based LSCs as a future energy solution and optical devices. It delves into the operating principles, theoretically attainable energy, materials, and optical structure developments, as well as potential applications of LSCs. Additionally, the review discusses challenges associated with QD–LSCs and outlines future research directions. We believe that this comprehensive review provides insights into the current status and prospects of LSCs employing QDs, serving as a valuable resource for researchers and professionals in the field. [ABSTRACT FROM AUTHOR]

This study introduces a scalable synthesis of ammonia through photochemical reactions, wherein nitrogen-fixing bacterial cells, Azotobacter vinelandii (A. vinelandii), form hybrids with colloidal quantum dots (QDs). Irradiation of the QD-A. vinelandii hybrids with visible light is found to significantly enhance ammonia production efficiency. The inherently low ammonia conversion rate of wild-type A. vinelandii is substantially increased upon incorporation of QDs. This increase is attributed to the electron transfer from QDs within the bacterial cells to intracellular bio-components. Transferring this chemistry to a large-scale reaction presents a tremendous challenge, as it requires precise control over the growth conditions. We explore the scalability of the QD-A. vinelandii hybrids by conducting the photochemical reaction in a 5-L fermentor under various parameters, such as dissolved oxygen, nutrient supply, and pH. Interestingly, ammonia was produced in media depleted of carbon sources. Consequently, a two-step fermentation process was designed, enabling effective ammonia production. Our findings demonstrate that the QD-A. vinelandii hybrid system in a bioreactor setup achieves an ammonia turnover frequency of 11.96 s−1, marking a more than sixfold increase in efficiency over that of nitrogenase enzymes alone. This advancement highlights the potential of integrating biological and nanotechnological elements for scalable ammonia production processes. [ABSTRACT FROM AUTHOR]

Recent advances in skin-attachable electronics have attracted substantial interest because of their potential in various fields such as robotics, healthcare, and wearable technology. Among various electroluminescent (EL) devices, quantum dot light-emitting diodes (QLEDs) are promising for next-generation displays due to their superior color purity, high brightness, excellent efficiency, high stability, and ultrathin form factors, making them promising for flexible electronic applications. This review outlines the recent progresses in QLEDs for skin-attachable electronics. First, materials selection and various structural designs that impart mechanical flexibility into QLEDs are discussed. We also discussed the design strategies of flexible displays based on the array of QLEDs. Then, we summarize skin-attachable displays based on the flexible QLEDs, including the integration with sensors capable of detecting various signals. The discussion includes the promising role of skin-attachable QLEDs in healthcare, particularly their potential as wearable light sources for monitoring biologic signals. Overall, this review article highlights the remarkable progress made in the skin-attachable QLEDs. [ABSTRACT FROM AUTHOR]

Monitoring the concentration of antibiotics rapidly and cost-effectively is crucial for accurate clinical medication and timely identification of drug-induced illnesses. Here, we constructed a novel fluorescent assay kit to monitor Zavicefta, an effective antibiotic composed of avibactam (AVI) and ceftazidime (CFZ) to treat carbapenem-resistant gram-negative bacteria infections. AVI can emit fluorescence, but CFZ cannot. To enable simultaneous measurement of both in one kit, we designed molecularly imprinted polymer (MIP) modified quantum dots (QDs) for CFZ determination. MIPs have received significant attention as an artificial antibody due to their exceptional specificity for various targets, particularly drugs with small molecular weight. Under the excitation wavelength of 350 nm, the detection process involves a decrease in QDs' fluorescence signal at 600 nm owing to the "gate effect" between MIP and CFZ and the internal filtration effect between CFZ and QDs. Simultaneously, a fluorescence emission characteristic peak at 420 nm for AVI emerges. In addition, to simplify the operation procedure and improve determination throughput, the detection agents were incorporated into a hydrogel and placed in a 96-well plate, enabling concurrent quantification of AVI and CFZ within the respective range of 80–1000 μM and 1–1000 μM. The developed assay kit successfully determined AVI and CFZ in human serums and therapeutic drug monitoring in a live rabbit model. Recoveries of AVI and CFZ were 92.7–114%, with relative standard deviations below 6.0%. Moreover, a smartphone was employed to read the fluorescence signals, which was beneficial for cost reduction and out-of-lab analysis. This study will deliver a pragmatic resolution to developing high-throughput assay kits for drug determination. [ABSTRACT FROM AUTHOR]

In this work, the magnetic and thermodynamic properties of dilute magnetic semiconductor quantum dots of cylindrical geometry are investigated. The eigenvalue of the quantum system we are considering is obtained by solving the one-electron Schrödinger equation within the framework of the effective mass approach. Then, taking into account the energy spectrum, expressions for thermodynamic quantities and magnetic susceptibility are obtained. The behavior of these expressions depending on temperature is studied using the parameters B , x , R 0 and L 0 . Based on the results obtained, it is established that the average energy, free energy, heat capacity, entropy and magnetic susceptibility at low temperatures depend on the parameter x . Also at low temperatures, when x = 0 , the average energy and free energy exhibit a linear relationship. With increasing temperature, this dependence becomes nonlinear. For x ≠ 0 , the dependence of the average energy and free energy on temperature is a rapidly increasing nonlinear function. In addition, when x ≠ 0 , magnetic susceptibility reaches a maximum at low temperatures. The peak height increases with x and disappears when x = 0 . The peak of magnetic susceptibility decreases as the magnetic field increases when x ≠ 0 and shifts toward higher temperatures. The specific heat forms a Schottky peak at low temperatures and asymptotically approaches C v = 3 k B at high temperatures. [ABSTRACT FROM AUTHOR]

Currently, the application of synthetic biology to artificially manipulate and utilize organisms for the synthesis of desired products such as nanomaterials with excellent fluorescence properties is attracting considerable attention. However, it is still difficult to obtain designed products efficiently due to insufficient knowledge of the biosynthetic mechanisms. The thioredoxin (TRX) and glutathione (GSH) pathways are generally conserved thiol-reductase systems that protect organisms from oxidative stress and are involved in selenium (Se) metabolism. In this study, we revealed the pivotal role of cytoplasmic TRX pathway in regulating the metabolism of Na2SeO3 during the live-cell synthesis of cadmium-selenium quantum dots (CdSe QDs) in Saccharomyces cerevisiae by regulating the expression level of genes related to TRX pathway and measuring the intracellular content of selenocysteine (SeCys). The determination of SeCys metabolism in yeast with GSH pathway-related genes deleted demonstrated that the TRX pathway played a more significant role in SeCys metabolism than GSH pathway. A 6.4-fold enhancement in the synthetic yield of CdSe QDs was achieved through the overexpression of TRX pathway-related genes, improvement of synthetic procedure, and supplementation of GSH based on the understanding of biological metabolism. Exploring the mechanism of CdSe QDs live-cell synthesis facilitates the precise manipulation of biological processes for the synthesis of inorganic nanomaterials. [ABSTRACT FROM AUTHOR]

This paper describes the design of a quantum beam splitter that transforms the state of a spatial photonic qubit in two modes due to the exchange of energy between the modes and quantum dots (QDs). By controlling the interaction time, it is possible to obtain the required superposition of the basic single-photon states of the qubit at the output of the device. In addition, the beam splitter allows the generation of entangled two-photon NOON states. Using the Förster effect to control the energy exchange between QDs makes it possible to increase the intermodal distance and suppress unwanted direct interaction of the modes. As an example, a beam splitter based on a two-dimensional photonic crystal (PC) with temperature and structural frequency tuning is considered. [ABSTRACT FROM AUTHOR]

Quantum dot infrared photodetectors (QDIPs) have garnered significant interest from researchers over recent decades. The enhancement of QDIP absorption has increasingly become a focal point of investigation. Employing metal–semiconductor-metal (MSM) structures to boost absorption represents a prevailing trend in contemporary research. In this study, we introduce the MSM structure to the conventional QDIP and design a bespoke metal grating structure for it. This enhanced QDIP markedly boosts the absorptance of incident light in the near-infrared (NIR) region. Simulations using COMSOL software reveal that the conventional QDIP demonstrates an absorption peak of 46.11% at 351 THz. In contrast, the enhanced QDIP displays absorption peaks of 99.23%, 99.19%, 97.01%, and 89.23% at frequencies of 137 THz, 217 THz, 294 THz, and 367 THz, respectively. The maximum absorptance of the enhanced QDIP reaches 99.23%, which is 2.15 times greater than that of the conventional QDIP. Incorporating the MSM structure substantially enhances the absorptance of the QDIP in the near-infrared region. It is anticipated that this study will offer valuable theoretical guidance in the realm of near-infrared detection. [ABSTRACT FROM AUTHOR]

There is increasing interest in the use of cannabidiol (CBD) as a potential therapeutic for alleviating chronic pain in cancer patients. Reliable determination of CBD content tailored to individual patients is essential for effective administration. Additionally, there is a growing need for rapid and portable detection methods for food products containing trace amounts of cannabis-derived compounds. Electrochemical technique offer a promising approach for fast and straightforward analytical identification of compounds like CBD. This study presents the fabrication of electrochemical sensor utilizing Fe2O3 quantum dots (QDs) – Co3O4 nanowires (NWs) as a sensing layer in a modified silver electrode. Chemical and structural analyses including energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS) confirm the excellent decoration of Fe2O3 QDs on the Co3O4 NW surfaces. The Fe2O3 QDs-Co3O4 NWs exhibit electrochemical activity based on cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) measurements. The sensor demonstrates a sensitivity of 1.21 mA•mM⁻¹•mm⁻¹ with strong linearity over the range of 0.02–0.1 mM (R2 = 0.9991) and a low detection limit of 0.67 µM. The enhanced electrochemical response of the Fe2O3 QDs-Co3O4 NWs sensing layer is attributed to the increased number of active sites resulting from the heterostructure formed by the two semiconductor crystals. A charge-transfer mechanism driven by stochastic processes is proposed to explain the electrochemical sensing behavior. [ABSTRACT FROM AUTHOR]

Quantum emissions, such as single photon emission (SPE) and superradiance (SR), are fundamental ingredients of quantum optical technology. The quest for efficient, controllable, and scalable quantum emitters is crucial for successfully implementing various quantum technologies, such as quantum computing, secure quantum communication and high-precision metrology. Recently, perovskite quantum dots (PQDs) have emerged as highly efficient sources of quantum emission due to their excellent optical properties, including near 100% quantum yield, high optical absorbance, and tunable bandgaps covering the entire visible range. This Prospective introduces the principles of quantum emissions, including SPE and SR, and summarizes recent progress in exploring quantum emissions in PQDs. We focus on the prospects, advantages, and challenges associated with the quantum emissions from PQDs. This Prospective concludes with an outlook on PQDs in advancing future quantum technologies. [ABSTRACT FROM AUTHOR]

The paper considers an algorithm for entangling the states of an exciton qubit on a single quantum dot and a charge qubit on a double quantum dot. The possibility of performing a conditional two-qubit CNOT operation using laser transitions and the Förster effect is analyzed. Estimates of the system parameters are given for which this operation is implemented with a probability close to unity. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the optical properties of ZnSe/ZnS non-concentric core–shell quantum dots (CSQDs). The numerical method used in this work is based on a combination of coordinate transformation and finite difference method (FDM) to solve the three dimensions of the Schrödinger equation. The optical properties are obtained using the compact density matrix formalism. The influence of different dimensions of the non-concentric CSQD, the position of a core material and the effect of different values of the incident optical intensity I on the optical properties of the CSQD are investigated. The results obtained indicate that the oscillator strength, absorption coefficient and refractive index changes are strongly dependent on the size of the CSQD. The magnitude of both the total absorption coefficient and the refractive index decreased as the incident optical intensity increased. In addition, the resonance peaks for the absorption coefficient and refractive index changes shift towards higher energies when we move from concentric to non-concentric core–shell quantum dots. [ABSTRACT FROM AUTHOR]

The long-lived green luminescence of human bone (that has been heated to 600 °C for a short duration) is attributed to a carbon quantum dot material (derived from collagen) encapsulated and protected by an inorganic matrix (derived from bone apatite) and is more intense in dense rigid and crystalline parts of (healthy) human bones. The strong collagen-apatite interaction results (upon decomposition) in a protective inorganic environment of the luminescent centers allowing long-lived triplet-based emission of a carbon (quantum) dot-like material at room temperature, as well as resilience against oxidation between 550 and 650 °C. The graphitic black phase (obtained upon heating around 400 °C) is a precursor to the luminescent carbon-based material, that is strongly interacting with the crystalline inorganic matrix. Human bone samples that have been heated to 600 °C were subjected to steady-state and time-resolved spectroscopy. Excitation-emission matrix (EEM) luminescence spectroscopy revealed a broad range of excitation and emission wavelengths, indicating a heterogeneous system with a broad density of emissive states. The effect of low temperature on the heat-treated bone was studied with Cryogenic Steady State Luminescence Spectroscopy. Cooling the bone to 80 K leads to a slight increase in total emission intensity as well as an intensity increase towards to red part of the spectrum, incompatible with a defect state model displaying luminescent charge recombination in the inorganic matrix. Time-resolved spectroscopy with an Optical Multichannel Analyzer (OMA) and Time Correlated Single Photon Counting (TCSPC) of these samples showed that the decay could be fitted with a multi-exponential decay model as well as with second-order decay kinetics. Confocal Microscopy revealed distinct (plywood type) structures in the bone and high intensity—fast decay areas as well as a spatially heterogeneous distribution of green and (fewer) red emissive species. The use of the ATTO 565 dye aided in bone-structure visualization by chemical adsorption. Conceptually our data interpretation corresponds to previous reports from the material science field on luminescent powders. [ABSTRACT FROM AUTHOR]

Recent advancements in quantum photonic circuits have significantly influenced the field of quantum information processing. The pursuit of an integrated quantum photonic circuit that offers an active, stable platform for large-scale integration and high processing efficiency remains a key objective. The grating coupler, as a crucial element for an efficient transformation output interface in the integrated quantum photonic circuits, presents significant potential for practical applications. Here, we demonstrate the integration block of a highly efficient shallow-etched focusing apodized grating coupler with indium arsenide (InAs) quantum dots (QDs) in gallium arsenide (GaAs) on a SiO2 substrate for active quantum photonic circuits. The designed grating couplers possess a high efficiency over 90% in the broadband (900–930 nm) from the circuit to free space, and a nearly-perfect match with the fiber mode. Experimentally, the efficiency to free space reaches 81.8%, and the match degree with the fiber mode is high up to 92.1%. The proposed integration block offers the potential for large-scale integration of active quantum photonic circuits due to its stable solid substrate and highly performant output for quantum measurements. [ABSTRACT FROM AUTHOR]

We consider a theoretical model of a quantum node that implements a two-qubit controlled-NOT (CNOT) operation on photonic qubits with spatial encoding. Each of the qubits is represented by a pair of modes that support an arbitrary superposition of single-photon states. The active element of the node is a single or double quantum dot (QD) with a tunable frequency, coherently exchanging an energy quantum with the modes. The spectral characteristics of the elements of the quantum node are simulated. The probability of performing a controlled inversion of the qubit state is calculated, depending on the system parameters. [ABSTRACT FROM AUTHOR]

We theoretically study the polarization of plasmonic fields in a hybrid nanosystem composed of three different metallic nano ellipsoid and a semiconductor quantum dot. The components of the hybrid nanosystem interact with three electromagnetic fields and one another via dipole-dipole interactions. We derive the density matrix equations at a steady state for the description of the optical properties of the hybrid nanosystem. The polarization of the plasmonic fields induced on the prolate, spherical, and oblate nano ellipsoid is calculated. We find that the polarization of the plasmonic fields depends on the number of the metallic nanoparticles (ellipsoid), the depolarization factor of the metallic nano ellipsoid, the direction of the plasmonic field, and the metallic nano ellipsoid parameters of the hybrid nanosystem. The phenomena of electromagnetically induced transparency (EIT) and electromagnetically induced transparency with amplification (EITA) are obtained in this work. [ABSTRACT FROM AUTHOR]

Equations are obtained for the quantum distribution functions over discrete states in systems of non-interacting fermions and bosons with an arbitrary, including small, number of particles. The case of systems with two levels is considered in detail. The temperature dependences of entropy, heat capacities and pressure in two-level Fermi and Bose systems are calculated for various multiplicities of degeneracy of levels. [ABSTRACT FROM AUTHOR]

The interplay between superconductivity and the Kondo effect has stimulated significant interest in condensed matter physics. They compete when their critical temperatures are close and can give rise to a quantum phase transition that can mimic Majorana zero modes. Here, we have fabricated and measured Al-InSb nanowire quantum dot-Al devices. In the Kondo regime, a supercurrent-induced zero-bias conductance peak emerges. This zero-bias peak shows an anomalous negative magnetoresistance (NMR) at weak magnetic fields. We attribute this anomalous NMR to quasiparticle trapping at vortices in the superconductor leads as a weak magnetic field is applied. The trapping effect lowers the quasiparticle-caused dissipation and thus enhances the Josephson current. This work connects the vortex physics and the supercurrent tunneling in Kondo regimes and can help further understand the physics of Josephson quantum dot system. [ABSTRACT FROM AUTHOR]

In this work, we study the energy levels of electrons and holes of InAs quantum dots inside InP/InAs 0.25 P 0.75 /InP semiconductor nanowires. Taking into account the nonparabolicity of the dispersion law, the energy levels are calculated in two different ways. The change in the energy levels of a quantum dot at different positions inside a quantum nanowire is considered. The energy levels of semiconductor nanowire of various sizes are studied at a constant size. Changes in the energy levels of a quantum nanodot of a cubic shape are found when its size changes from 5 to 25 nm, located inside a quantum nanowire with a square section of 25 × 25 nm. [ABSTRACT FROM AUTHOR]

Present work inspects the role of spatial impurity spread (SIS) on oscillator strength (OS) and two nonlinear optical (NLO) properties of GaAs quantum dot (QD) containing impurity. The NLO properties include total optical absorption coefficient (TOAC) and the total optical refractive index change (TORIC). The said properties are studied under the influence of Gaussian white noise (GWN) that has been applied to the doped QD by means of additive and multiplicative routes. The study manifests the delicate interplay between noise and SIS that finally designs the NLO properties. TOAC and TORIC reveal red-shift as SIS enhances both with and without noise. OS, however, shows steady fall with enhancement of SIS. The study also indicates plausible ways of attaining very large NLO response by applying GWN in a particular pathway. Depending upon the application of noise and its route of introduction, the OS and the NLO properties can either be depleted or amplified to different extents in comparison with the noise-free situation. [ABSTRACT FROM AUTHOR]

We study the absorption coefficient of a diluted magnetic semiconductor ellipsoidal quantum dot with Rashba spin–orbit coupling. The Schrödinger equation for a one-electron ellipsoidal quantum dot was solved within the framework of the effective mass approximation method. The wave vector and electron energy found during the solution were used to find an expression for the absorption coefficient. The article examines intraband optical transitions relative to changes in external parameters. The decrease in the absorption coefficient as a function of the energy of the incident photon was studied at different values of the magnetic field, the Rashba parameter, temperature, concentration of Mn atoms and the radius of the ellipsoid. According to the results obtained, these parameters significantly affect intraband optical transitions. [ABSTRACT FROM AUTHOR]

The nonspecific nature of cancer drug delivery often results in substantial toxic side effects during treatments for breast cancer. To mitigate these negative outcomes, our approach involves loading methotrexate (MTX) within carbon quantum dots (CQDs) synthesized from folic acid, which are then enveloped in exosomal membranes obtained from breast cancer cells (Ex@MTX-CQDs). Analysis utilizing nanoparticle tracking techniques has demonstrated that these Ex@MTX-CQDs maintain the physical and biochemical properties of their exosomal precursors. The release profile of MTX indicated a restricted release percentage (less than 10%) under normal physiological conditions, which is contrasted by a more consistent release rate (approximately 65%) when emulating the conditions found within tumor tissues. The toxicological assessments have confirmed that the presence of exosomes combined with leftover folic acid significantly improves the delivery efficacy of MTX directly to the cancerous cells through the binding to folate and heparan sulfate proteoglycan receptors. This process results in increased disruption of the mitochondrial membrane potential and subsequently triggers apoptosis, ultimately leading to the destruction of cancerous cells. Our research could potentially contribute to the further innovation and application of nanocarriers derived from biological sources for the targeted treatment of breast cancer. [ABSTRACT FROM AUTHOR]

We study the confinement of a quantum particle to the squared cotangent potential in the background of global monopole spacetime. By dealing with s-states, we obtain the energy levels from the exact solutions to the Schrödinger equation. Then, we show that the topology of the global monopole spacetime influences the energy levels. Further, we show that there is a non-null revival time with regard to the squared cotangent potential and how it is influenced by the global monopole topology. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) were prepared by electro-chemical reaction method under reaction conditions such as time and current. The current is 30 mA and time is 3 h. The samples were analyzed using X-ray diffraction, transmission electron microspectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, UV–visible spectroscopy, and Hall effect. The results showed that the crystal size calculated by Debye–Scherrer's formula was 70 nm and a greater peak of 1577 cm−1 obtained from FTIR corresponded to C꞊C, which refers to CQDs. The generated energy surface state was measured, which is 3.17, 2.54, 2.33, and 2.01 eV, and the change in the size of surface state was measured, which is 3.372, 3.089, 2.891, and 2.685 nm, respectively, and the free carrier concentration was 5.008 × 108 cm−2, where it was the nanostructure. It was found by measuring the Hall effect that the CQDs were p-type. [ABSTRACT FROM AUTHOR]

In the filtered optical feedback system, a part of the emission of the laser is spectrally filtered, here by a Fabry–Perot (FP) filter, and then fed back into the quantum-dot (QD) laser cavity. This technique has been used in various applications such as inducing frequency dynamics in QD semiconductor lasers and studying the dynamical behavior of a QD semiconductor laser subject to delayed filtered optical feedback. We report on the systematical investigation of the steady-state regime and the dynamical behavior of a QD semiconductor laser subject to delayed FOF. The effects of the filter on the locking of the QD laser frequency to the external cavity modes are described. We report and observe hysteresis, bistability, and multistability and show that all these are well described by a set of rate equations for the coupled QD laser and FP cavity system. We also present a stability diagram that summarizes the dynamical behavior of the system. [ABSTRACT FROM AUTHOR]

The 2023 Nobel Prize in Chemistry was awarded to Aleksey I. Ekimov (prize share 1/3), Louis E. Brus (prize share 1/3), and Moungi G. Bawendi (prize share 1/3) for groundbreaking inventions in the field of nanotechnology, i.e., for the discovery and synthesis of semiconductor nanocrystals, also termed quantum dots, that exhibit size-dependent physicochemical properties enabled by quantum size effects. This feature article summarizes the main milestones of the discoveries and developments of quantum dots that paved the road to their versatile applications in solid-state lighting, display technology, energy conversion, medical diagnostics, bioimaging, and image-guided surgery. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of quantum nanostructures are determined by their sizes and energy states affected by external electric field. The IR subband optical absorption of zinc-blende GaN/AlN spherical quantum dots (QDs) is obtained from perturbed energy states. The static dielectric constant and associated functions for broadened general absorption in the strong absorptive region are obtained from an improved iterative density matrix. These functions are also verified via Kramers–Kronig relations for a 4 nm zinc-blende GaN/AlN heterocrystal QD. The dielectric constants obtained for QDs in this study are well-matched with the bulk dielectric constant of GaN. Additionally, it is observed that the electric field effect dominates at the above of excitonic radius, while size effects significantly alter subband energies for smaller QD radius. As a perturbative result, forbidden transition-peaks in the presence of the electric field are also obtained at sizes of QD radii 5 nm and 6 nm. [ABSTRACT FROM AUTHOR]

In the research, the effects of the Rashba spin–orbit interaction (SOI) and magnetic field have been studied on the electronic and optical properties of a Frost–Musulin (FM) quantum dot. For this goal, the Schrödinger equation has been analytically solved by the Nikiforov–Uvarov (NU) procedure, and the energy states and the wave functions have been analytically derived. Using the analytical relations for optical properties, the total refractive index change (RIC) and absorption coefficient (AC) are calculated under a magnetic field with the Rashba SOI. The findings show that both the Rashba SOI and the magnetic field have a strong effect on the energy levels, RIC, and AC. The Rashba SOI causes the energy states to split into two branches, up and down. The peak locations of the RIC and AC move to higher energies when the magnetic field and Rashba coupling are increased. [ABSTRACT FROM AUTHOR]

The stationary states of an electron in a nanosized semiconductor quantum dot of spheroidal shape with a deep confining potential are considered. The discrete energy spectrum and corresponding wave functions are very sensitive to the elongation, especially in the region of high eccentricity values. The main attention is paid to identifying the patterns of the radial-angular distribution of electron wave functions, which should play an important role in the angular distribution of photons emitted by the quantum dot. [ABSTRACT FROM AUTHOR]

Mixed-dimensional composite structures using zero-dimensional (0D) quantum dots (QDs) and two-dimensional (2D) transition metal dichalcogenides (TMDs) materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties. Here, we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide (WSe2)/CdSeS QDs monolayer/molybdenum disulfide (MoS2) (2D/0D/2D). Specifically, it exhibits an ambipolar photoresponse characteristic, with a negative photoresponse observed in the 400–600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength. It resulted in the high negative responsivity of up to 52.22 mA·W−1 under 400 nm, which is 163 times higher than that of the photodetector without CdSeS QDs. We also demonstrated the negative photoresponse, which could be due to increased carrier collision probability and non-radiative recombination. Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation. Consequently, we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots. Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, the impact of Ag–In–S quantum dots (QDs) on the dielectric and electro-optical characteristics of E7 nematic liquid crystal (NLC) is investigated. To realize the objective, various concentrations of Ag–In–S QDs (0.2, 0.4, 0.6, 0.8, and 1 wt%) were added to E7 NLC, and the resulting composites were then introduced into homogeneous, homeotropic, and twisted nematic aligned cells. The temperature dependence property of the parallel and perpendicular components of the dielectric constant (ɛ∥ & ε ⊥ ) for pure and QDs-doped NLCs was measured. ɛ∥ significantly enhanced in the presence of 0.8 wt% of the QDs, which led to a ~ 23% rise in the dielectric anisotropy of the system. The dielectric results demonstrated that NLC hosts prompt QDs to form self-assembled arrays within the NLC system. In addition, electro-optical measurements revealed the considerable impact of QDs doping on the reduction of threshold voltage (Vth). Importantly, a ~ 15% decrease in Vth was observed for NLC doped with 0.8 wt% of the QDs compared to pure NLC. Besides, the addition of QDs significantly accelerates the NLC electro-optical response. The switch-on and -off response times for the QDs-doped NLC cell were reduced by ~ 34% and ~ 41%, respectively, compared to those for the pure NLC cell. A combination of increased dielectric anisotropy, improved mutual interactions of components, and reduced rotational viscosity of the mixture may result in much faster electro-optical switching responses. The presented achievements in this study will be beneficial in the development of LC-based display panels as well as switchable smart windows. [ABSTRACT FROM AUTHOR]

The technology of RGBY micro resonant cavity light emitting diodes (micro-RCLEDs) based on quantum dots (QDs) is considered one of the most promising approaches for full-color displays. In this work, we propose a novel structure combining a high color conversion efficiency (CCE) QD photoresist (QDPR) color conversion layer (CCL) with blue light micro RCLEDs, incorporating an ultra-thin yellow color filter. The additional TiO2 particles inside the QDPR CCL can scatter light and disperse QDs, thus reducing the self-aggregation phenomenon and enhancing the eventual illumination uniformity. Considering the blue light leakage, the influences of adding different color filters are investigated by illumination design software. Finally, the introduction of low-temperature atomic layer deposition (ALD) passivation protection technology at the top of the CCL can enhance the device's reliability. The introduction of RGBY four-color subpixels provides a viable path for developing low-energy consumption, high uniformity, and efficient color conversion displays. [ABSTRACT FROM AUTHOR]

Gaining insight into nanostructure devices represents a crucial step in unlocking their full quantum potential. Solid-state quantum dots provide a practical and scalable foundation for accommodating qubits, which are essential for quantum information processing. In this context, we introduce a model involving a pair of qubits within a double quantum dot configuration. We extensively investigate its quantum coherence and the quantum-memory-assisted entropic uncertainty relation ( QMA - EUR ), considering the influence of the thermal environment and Rashba spin–orbit coupling. Our findings reveal a monotonic increase in QMA - EUR with rising temperatures (T), while the Jensen–Shannon coherence consistently decreases as T increases. Furthermore, fine-tuning the Rashba coupling can enhance the system's coherence and reduce measurement uncertainty. We show that obtaining higher measurement precisions is achievable when the two-qubit system, made up of the double quantum dots with Rashba interaction, demonstrates higher levels of coherence. Additionally, we demonstrate that adjusting other Hamiltonian parameters offers advantages in preserving quantum resources. These reported results indicate promising prospects for developing quantum technologies that leverage such a quantum dot system. [ABSTRACT FROM AUTHOR]

Entanglement purification is an important and useful tool in quantum communications that allows parties to enhance the entanglement of a set of less-entangled particles using local operations and classical communication. Utilizing photon polarization parity checks implemented through the coupling system between a single-sided cavity and a charged quantum dot, an entanglement purification scheme is proposed in this paper. The fidelity and the success probability of the scheme are calculated under bit-flip error channel and depolarizing channel, respectively. Furthermore, the impact of imperfect quantum-dot-cavity coupling system is investigated, and the feasibility is discussed. In the strong coupling and weak cavity side leakage regime, our scheme can approach the maximal fidelities and success probabilities in theory. So the scheme has potential applications in long-distance quantum communication with the development of relevant technologies. [ABSTRACT FROM AUTHOR]

In the paper, the electronic properties of a quantum dot (QD) using the Frost–Musulin potential model are investigated taking into account both an external magnetic field and electron–electron interaction. For this purpose, the Schrödinger equation (SE) is analytically solved without considering electron–electron interaction by employing the Nikiforov–Uvarov (NU) procedure, and the energy levels and wave functions are determined. Then, the singlet–triplet (ST) transition is studied for different values of magnetic fields. According to our results, Both the dot size and magnetic field have key roles in the ground state transition. The ST transition of the ground state moves to lower magnetic fields as the QD size is increased. However the transition occurs at higher magnetic fields when the potential depth is increased. The transition for small QD size occurs only from 1S to 3P. But by increasing the QD size, another transition is also observed from 1D to 3F. These transitions occur at smaller magnetic fields when the QD size is increased. [ABSTRACT FROM AUTHOR]

Present enquiry thoroughly explores the time-average excitation rate (TAER) of GaAs quantum dot (QD) pursuing the change in the anharmonicity binding energy (ABE) of the system and under the supervision of Gaussian white noise (GWN). The promotion of the ground state electronic density occurs due to various kinds of time-varying fluctuations viz. simple sinusoidal field (SSF), time-dependent confinement potential (TDCP), time-dependent magnetic field (TDMF), polychromatic radiation field (PRF), pulsed field (PF), chirped pulsed field (CPF), time-dependent anharmonicity constant (TDAC) and time-dependent noise strength (TDNS). GWN couples with the QD by additive and multiplicative modes. The work analyzes the consequence of joint influence of a few parameters that guides the attributes of the TAER diagrams. These parameters involve ABE, inclusion of GWN in a given pathway, the parity of the anharmonic potential and the type of the time-dependent perturbations. The TAER curves are enriched with steadfast rise, steadfast diminish, maximization (relevant to generation of large nonlinear optical properties), minimization and saturation (suggesting dynamic freezing). The findings highlight the utility of different kinds of time-dependent fluctuations to fine-tune the TAER among the GaAs QD eigenfunctions when the ABE of QD carries out a continual change. [ABSTRACT FROM AUTHOR]

A spectral model is constructed for the luminescence of a two-component exciton-activated quantum dot (QD)–spheroidal plasmon nanoparticle (NP) system in a homogeneous external magnetic field in the approximation of a dipole electric polarizability tensor of the nanoparticle with dissipation of the exciton energy in the NP taken into account. A tensor representation of the dielectric permeability of the magnetized electron plasma of the metal is used, which is responsible for the formation of the characteristics of the electric field in the spheroid. It is found that with a change in the eccentricity of the spheroid, the luminescence spectrum of the system changes, reflecting the effect of the external magnetic field on both the radiative and the dissipative properties of the binary QD–NP complex. [ABSTRACT FROM AUTHOR]

We theoretically investigate the Seebeck and Peltier effect across an interacting quantum dot (QD) coupled between a normal metal and a Bardeen–Cooper–Schrieffer superconductor within the Coulomb blockade regime. Our results demonstrate that the thermoelectric conversion efficiency at optimal power output (optimized with respect to QD energy level and external serial load) in NQDS nanodevice can reach up to 58 % η C , where η C is Carnot efficiency, with output power P max ≈ 35 fW for temperature below the superconducting transition temperature. Further, the Peltier cooling effect is observed for a wide range of parameter regimes, which can be optimized by varying the background thermal energy, QD level energy, QD-reservoir tunneling strength, and bias voltage. The results presented in this study are within the scope of existing experimental capabilities for designing miniature hybrid devices that operate at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Biosynthesized semiconductor quantum dots (QDs) have bright fluorescence, adjustable particle sizes, and environmental friendliness, endowing them with convenience and potential for biological applications. Due to the unclear mechanism of the cellular environment on the live-cell synthesis of QDs, it is still difficult to regulate their optical properties. Here, the critical role of the intracellular redox environment in regulating the fluorescence properties of biosynthesized CdSe QDs in Staphylococcus aureus (S. aureus) has been elucidated. The glutathione peroxidase (GPx) activity directly affects the intracellular H2O2 produced in the SeO32− reduction, which further manipulates the glutathione redox cycle to determine the content of low-valence Se-intermediates. As a result, the fluorescence intensity of the synthesized CdSe QDs increases by 60% in the GPx overexpressed cells. The cellular redox potential that is controlled by the GSH redox cycle provides the driving force for the reduction of SeO32−, facilitating the synthesis of CdSe QDs in S. aureus cells. The proposed mechanism of the cellular redox state provides a new perspective for regulating the synthesis of semiconductor nanomaterials in live cells. [ABSTRACT FROM AUTHOR]

Tetragonal graphene nano-capsule (TGC), a novel stable carbon allotrope of sp2 hybridization is designed and doped with phosphorus (P) to study the O3 and SO2 gas sensitivity via density functional theory calculation. Real frequencies verified the natural existence of both TGC and P-doped TGC (PTGC). Both TGC and PTGC suffer structural deformations due to interaction with O3 and SO2 gases. The amount of charge transfer from the adsorbent to the gas molecule is significantly greater for O3 adsorption than SO2 adsorption. The adsorption energies for TGC + O3 and PTGC + O3 complexes are − 3.46 and − 4.34 eV respectively, whereas for TGC + SO2 and PTGC + SO2 complexes the value decreased to − 0.29 and − 0.30 eV respectively. The dissociation of O3 is observed via interaction with PTGC. A significant variation in electronic energy gap and conductivity results from gas adsorption which can provide efficient electrical responses via gas adsorption. The blue/red shift in the optical response proved to be a way of detecting the types of adsorbed gases. The adsorption of O3 is exothermic and spontaneous whereas the adsorption of SO2 is endothermic and non-spontaneous. The negative change in entropy verifies the thermodynamic stability of all the complexes. QTAIM analysis reveals strong covalent or partial covalent interactions between absorbent and adsorbate. The significant variation in electrical and optical response with optimal adsorbent-gas interaction strength makes both TGC and PTGC promising candidates for O3 and SO2 sensing. [ABSTRACT FROM AUTHOR]

The current study reports a novel synthesis of bismuth oxybromide (BiOBr) quantum dots (QDs) doped with different concentrations (3 and 6 wt%) of silver (Ag) and a fixed amount of polyvinylpyrrolidone (PVP). This research investigated the catalytic and antibacterial activity with evidential molecular docking analysis of Ag/PVP doped BiOBr QDs. The Ag and capping agent (PVP) were added to BiOBr as they regulate the growth of QDs and prevent their agglomeration that caused to increase in the catalytic and antibacterial activity. These binary dopants-based BiOBr QDs can be an ideal catalyst for disintegrating methylene blue dye and a potential inhibitor against the multiple drug resistance (MDR) Escherichia coli (E. coli) pathogen. Notably, 6% Ag/PVP doped BiOBr showed a significant catalytic reduction of methylene blue (MB) in a basic medium (pH ~ 12) compared to other environments. The results of the molecular docking investigation suggested that Ag/PVP-doped BiOBr QDs might be inhibitors of FabH and deoxyribonucleic acid (DNA) gyrase from E. coli, which was consistent with their In vitro antimicrobial activity. [ABSTRACT FROM AUTHOR]

Charge current through a single quantum dot coupled to a source and drain with an applied bias voltage is studied. The current–voltage characteristics are calculated using our treatment within the Anderson model. The dependence of the current–voltage characteristics on the Coulomb energy, temperature, gate voltage, and magnetic field is examined. A clear dependence of all the practical requirements, functions and parameters considered in our work to describe the electron transport throughout the quantum dot is highlighted. Our results can be experimentally realized and it is easy to tune practical parameters to determine the correlation regime for a certain spin. [ABSTRACT FROM AUTHOR]

An organo-modified ordered layered structure with three-dimensional close packing based on colloidal quantumsized particles (QP) of InSb, PbS, CdSe semiconductors and Langmuir–Blodgett films has been fabricated and studied. According to the current-voltage characteristics (CVC) of single-electron transport in the model of a nanocell with a linear chain QP across the layers, the processes limiting conductivity were established: emission–injection tunneling from a probe into a nanoparticle, motion in a nanoparticle determined by the establishment of an electronic wave process in it, and tunneling through a nanogap between nanoparticles. Quasi-periodic oscillations of the current and resonant peaks of quantum conductivity are observed on the I–V characteristics, which were estimated in the quantum wire model. For an even number of layers (QP, 2, or 4), the I–V characteristics were used to determine the attenuation of size quantization and the decrease in current due to the weak interaction of nanoparticles. With an odd number (3 or 5), the nanochain acts as a single quantum thread with manifestations on the CVC similar to the cases of one QP. In this case, the motion of an electron can be considered as a one-electron charge wave. [ABSTRACT FROM AUTHOR]

In this research, structural, electronic and optical properties of ANBN quantum dots (QD) with N = 2,3,4 in the absence and presence of Cu impurity atom have been investigated based on density functional theory and using Siesta computational code. Local density approximation (LDA) is used for exchange–correlation functional. The band structure shows that ANBN QD structures have a semiconductor behavior. By adding Cu atom, a cross band with the Fermi level can be seen in the band structure, therefore, ANBN QD structures show semi-metallic behavior in the presence of Cu atom. The study of the optical properties of ANBN quantum dots and the calculation of their dielectric function, absorption coefficients and refractive index have been realized. Examining the optical results confirms that the transition threshold energy of quantum dots corresponds to their band gap value. [ABSTRACT FROM AUTHOR]

We are conducting a study on the energy levels of a magnetic circular quantum dot made of metal dichalcogenide MoS 2 , which is exposed to a perpendicular magnetic field. To obtain the eigenspinors analytically, we solve the Dirac equation for the K and K ′ valleys. By utilizing the Hamiltonian for low energies, we derive analytical expressions for the energy levels and apply boundary conditions at the interface. We explore four different configurations of the system and numerically analyze our findings. Specifically, we show the relationship between the energy levels, quantum dot radius, and magnetic field for both the K and K ′ valleys. We demonstrate that the energy levels depends on the spin-orbit interaction and on the quantum number m. In addition, for m ≠ 0 , due to the influence of the spin-orbit interaction of the quantum dot of MoS 2 , there is a degeneration of the valleys and spins, and this degeneracy is lifted if m = 0 . The resulting eigenenergies E nm exhibit a symmetric behavior between the valence and conduction bands. In addition, for m < 0 , the eigenenergies are independent of m but for m > 0 , they increase as long as m increases. Finally, we show that the radial probability exhibits a damped oscillatory behavior as the dot radius increases. Furthermore, the behavior of the radial probability is strongly dependent on both the quantum numbers n and m. [ABSTRACT FROM AUTHOR]

With the development of biofilms by various microorganisms, bacterial species are more and more resistant to antibiotics. Thus, the quest for finding novel antibiofilm agents continues to fight against these pathogenic infections. Carbon nanoparticles and nanocomposites such as carbon nanotubes, fullerenes, graphene oxide nanoparticles, carbon quantum dots, etc.; shows effective antibiofilm activities against different biofilm-forming bacteria and fungi. This is due to their shape and size which plays a major role in the disintegration of the extracellular polymeric matrix of the bacterial biofilms causing their inhibition. Carbon nanotubes are found to reduce the use of antibiotics as well as reduce the resistance possessed by these biofilms forming bacterial and fungal species, increase their bioavailability, and increase their capabilities for on-site drug delivery. The present review provides insight into the antibiofilm efficiencies of different carbon nanoparticles and nanocomposites and their mechanism of action. [ABSTRACT FROM AUTHOR]

Herein, new efficient photocatalysts composed of Cu doped NiS/ZnS quantum dots-composites were synthesized by coprecipitation technique for treatment of organic dyes. Treatment of dyeing-wastewater is an important issue to reduce the environmental pollution and providing a large quantity of pure water. The transmission electron microscope images of pure and Cu doped NiS/ZnS composites show quantum dots particles with size of 3–4 nm. The X-ray diffraction confirmed the formation of cubic ZnS and rhombohedral NiS. Optically, doping by 4 wt% Cu ions was reduced the band gap energy of ZnS from 3.4 to 2.98 eV, which improve the visible light absorption. 4 wt% Cu doped NiS/ZnS nanocomposite reveals a fast and remarkable photodegradation efficiency of 95%, 98% and 97% towards 20 ppm methyl green, methylene blue and Congo red during 60 min of sunlight irradiation. For three cycles, 4 wt% Cu doped NiS/ZnS nanocomposite exhibits significant photodegradation activities of 98%, 92% and 85%, respectively. The improvements of the photocatalytic activity of Cu doped NiS/ZnS nanocomposite can be attributed to some factors including visible-light absorption and charge carriers separation. The Cu doping improves the visible light response of ZnS through reducing the band gap which reinforce the number of the excited electron-hole pairs. Too, Cu ions act as trapping centers (Cu2+ + e → Cu+) which boost the separation of the excited electron-hole pairs and consequently improve the photodegradation activity. This study point out that the integration of p-n heterostructure and doping strategies are efficient for deign of photocatalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]