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The transformation of colloidal semiconductor magic-size clusters (MSCs) from zinc to cadmium chalcogenide (ZnE to CdE) at low temperatures has received scant attention. Here, we report the first room-temperature evolution of CdE MSCs from ZnE samples and our interpretation of the transformation pathway. We show that when prenucleation stage samples of ZnE are mixed with cadmium oleate (Cd(OA)₂), CdE MSCs evolve; without this mixing, ZnE MSCs develop. When ZnE MSCs and Cd(OA)₂ are mixed, CdE MSCs also form. We propose that Cd(OA)2 reacts with the precursor compounds (PCs) of the ZnE MSCs but not directly with the ZnE MSCs. The cation exchange reaction transforms the ZnE PCs into CdE PCs, from which CdE MSCs develop. Our findings suggest that in reactions that lead to the production of binary ME quantum dots, the E precursor dominates the formation of binary ME PCs (M = Zn or Cd) to have similar stoichiometry. The present study provides a much more profound view of the formation and transformation mechanisms of the ME PCs.

The formation of interfacial chemical bonding in heterostructures plays an important role in the transport of carriers. Herein, we firstly prepared ultrathin InVO4 nanosheet (Ns) with a thickness of 1.5 nm. Diethylenetriamine-modified CdSe (CdSe-DETA) nanobelts are in-situ deposited on the surface of ultrathin InVO4 Ns to build a InVO4/CdSe-DETA step-scheme (S-scheme) heterojunction photocatalysts. The protonated DETA acts as an amine-bridge to promote the formation of a tight chemical bond at the interface of InVO4/CdSe-DETA, thereby promoting the transfer of carriers at the interface. For photocatalytic CO2 reduction, the rationally designed InVO4/CdSe-DETA S-scheme photocatalyst exhibits a remarkable CO generation rate of 27.9 µmol h−1 g−1 at 420 nm, which is 3.35 and 3.39 times higher than that of CdSe-DETA and InVO4 Ns, respectively. The new method by using interfacial chemical bonding to facilitate interfacial charge transportation provide a promising strategy for improve photocatalysis.

Nanocomposites offer the desired properties with multi-functionality behavior. Hydroxyapatite (HAP), cadmium selenide (CdSe), and graphene oxide (GO) were combined in mono, di, and tri phases compositions. The morphology, structure, and chemical composition were investigated for HAP, CdSe, HAP/CdSe, HAP/GO and HAP/CdSe/GO using X-ray diffraction (XRD), transmission electron microscope, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). XRD shows that the crystallite size increased from 28 nm to 37 nm. SEM analysis shows the roughness average (Ra) starts from 27.8 increases till 28.8 nm for HAP and HAP/CdSe/GO, while the average maximum height of the roughness (Rtm) starts from 214.2 to 212.7 nm. The existence of HAP, CdSe, and GO was confirmed with XPS, EDX, and FTIR. The polarization behavior was investigated and the corrosion current density (Icorr) of the ternary nanocomposite reached 3.7 µA/cm2, while potential corrosion reached around − 0.3 V. It was found that the release of Cd2+ and Ca2+ ions increased upon the time of exposure up to around 23± 3 and 132 ± 4 ppm, respectively. The cell viability of osteoblasts human cell line toward the ternary nanocomposite reached 95.1 ± 3%. The antibacterial activity was studied and it was found that the inhibition zone reached around 20.4 ± 1.1 and 21.4 ± 0.9 mm against E. coli and S. aureus, respectively.

In this paper, we predict the nucleation phase of as-synthesized manganese (Mn) doped cadmium selenide (CdSe) quantum dots (QDs) at an intrinsic physical size of 3 (± 0.1 – 0.9) nm via photoluminescence (PL) studies. The nucleation phase was analyzed at temporal evolution (16, 46 and 90 mins) and temperature (210, 215 and 220 ºC) below the CdSe QDs reaction temperature (210 and 215 ºC) to it reaction temperature (220 ºC). The PL spectra`s observed to be against the QDs ripening behaviour of QDs since there are no prominent red-shift of PL spectra`s. However, the intensity of PL spectra`s shows to be varied with different temperatures and times.

The optoelectronic properties of metal chalcogenide colloidal nanoplatelets are often interpreted in terms of excitonic states. However, recent spectroscopic experiments evidence the presence of trion states, enabled by the slow Auger recombination in these structures. We analyze how the presence of an additional charge in trions modifies the emission energy and oscillator strength as compared to neutral excitons. These properties are very sensitive to dielectric confinement and electronic correlations, which we describe accurately using image-charge and variational Quantum Monte Carlo methods in effective mass Hamiltonians. We observe that the giant oscillator strength of neutral excitons is largely suppressedin trions. Both negative and positive trions are redshifted with respect to the exciton, and their emission energy increases with increasing dielectric mismatch between the platelet and its surroundings, which is a consequence of the self-energy potential. Our results are consistent with experiments in the literature, and assess on the validity of previous theoretical approximations., submitted

CdSe layers having high photosensitivity (photocurrent to dark current ratio of 6.2 × 104) and an extremely low carrier concentration (9 × 1011 cm–3) have been grown on muscovite mica by thermal evaporation in a quasi-closed system. These results are of interest for producing materials for position-sensitive semiconductor photodetectors based on CdSe layers. We have demonstrated that the 78-K cathodoluminescence spectra of the cadmium selenide layers grown at 853 K have a single line, corresponding to radiative annihilation of free A-excitons. The spectra of the layers grown at 833 K show a line of free A-excitons and its first phonon replica.

High resolution and wide color gamut are two key requirements for novel display technologies. Owing to the distinguishing advantages over conventional displays, such as intrinsic wide color gamut and the possibility to achieve high resolution, quantum dot light-emitting diodes (QLED) have drawn considerable attention in recent years. On the other hand, indium phosphide quantum dots (InP QDs) have shown a great potential as a replacement for cadmium selenide (CdSe) QDs in display applications due to the inherent toxicity of cadmium-based QDs. In this study, we investigate a top-emission InP-based green QLED with optimized angular distribution. By adjusting the electrical and optical architecture, the device exhibits improved properties with a maximum current efficiency of 30.1 cd/A and a narrowed full width at half maxima (FWHM)of 31 nm, which are the best results ever reported to our knowledge.

Divergent interpretations have appeared in the literature regarding the structural nature and evolutionary behavior for photoluminescent CdSe nanospecies with sharp doublets in optical absorption. We report a comprehensive description of the transformation pathway from one CdSe nanospecies displaying an absorption doublet at 373/393 nm to another species with a doublet at 433/460 nm. These two nanospecies are zero-dimensional (0D) magic-size clusters (MSCs) with 3D quantum confinement, and are labeled dMSC-393 and dMSC-460, respectively. Synchrotron-based small-angle X-ray scattering (SAXS) returns a radius of gyration of 0.92 nm for dMSC-393 and 1.14 nm for dMSC-460, and indicates that both types are disc shaped with the exponent of the SAXS form factor equal to 2.1. The MSCs develop from their unique counterpart precursor compounds (PCs), which are labeled PC-393 and PC-460, respectively. For the dMSC-393 to dMSC-460 transformation, the proposed PC-enabled pathway is comprised of three key steps, dMSC-393 to PC-393 (Step 1), PC-393 to PC-460 (Step 2 involving monomer addition), and PC-460 to dMSC-460 (Step 3). The present study provides a framework for understanding the PC-based evolution of MSCs and how PCs enable transformations between MSCs.

Electrochemical charge/discharge mechanisms in the electrophoretically deposited CdSe quantum dot (QD)film electrodes in NBu4PF6 acetonitrile solution have been investigated. The films were deposited from CdSe colloidal solution in nitrobenzene at variable QD size (diameter) from 3.4 to 6.3 nm onto transparent conducting glass substrates. Electrochemical behavior and optical response were characterized by cyclic voltammetry (CV) and in situ absorption spectroscopy. Electrochemical charging under an inert gas atmosphere results in a reversible color change (electrochromism), due to the bleach of exciton absorption with 0.3 optical density changes. The mechanism of electrochemical charging comprises electron transfer from conducting substrate to QD, interparticle transfer and also electron capturing by acceptors in solution. The introduction of a strong electron acceptor (O2) into the solution results in a suppression of electrochromism. The influence of oxygen is rather reversible which is observed from recovered electrochromic behavior after electrolyte resaturation with argon.

In this article, we theoretically demonstrate highly efficient cadmium telluride (CdTe)-based dual-heterojunction solar cells (DHSCs) with incorporating cadmium selenide (CdSe) and antimony selenide (Sb2Se3), separately as back surface field (BSF) layer using SCAPS-1D simulator. The impacts of various physical parameters have been investigated in details on the photovoltaic performance of the designed cells. It is found that the power conversion efficiency (PCE) of the pristine CdTe solar cell significantly increases by the use of CdSe and Sb2Se3 BSF layers. The optimized PCE of the CdTe solar cell increases from 21.29% for pristine SC to 31.11% with Voc = 1.15 V, Jsc = 30.66 mA/cm2 and FF = 88.57% owing to the use of CdSe BSF layer. On the other hand, the PCE of CdTe DH solar cell enhances to 44.14% with Voc = 1.05 V, Jsc = 49.23 mA/cm2 and FF = 85.71%, respectively by the use of Sb2Se3 BSF layer which is almost consistent with the detailed-balance limit of DHSC. These findings reveal that both the CdSe and Sb2Se3 could be promising BSFs for the fabrication of cost effective, highly efficient CdTe-based dual-heterojunction solar cells.

The quantum-chemical modeling of the synthesis process chemistry of CdS and CdSe in aqueos solutions was carried out. For that reason, the CdS synthesis simulation was carried out through the formation of Cd(II) complex forms with the trisodium citrate and ammonium hydroxide. At the CdSe synthesis, the sodium selenosulfate with and without trisodium citrate was used. It was established that this process passes through several intermediate stages with the transitional reactive complexes formation. On the basis of obtained data, the energy stages diagrams are constructed and the comparison of CdS and CdSe synthesis processes with various complexing agents has been carried out. The CdS and CdSe films were obtained by chemical synthesis method from an aqueous solution of cadmium salt, complexing and chalcogenizing agents. X-ray phase analysis confirmed the formation of desired compounds, which was predicted by modeling.

Nanosized semiconducting cadmium selenide particles were successfully distributed within the polymer matrix of polyvinyl alcohol (PVA) utilizing the method of heat induced chemical synthesis. The s...

The combination of semiconductor quantum dots (QD) and single-layer graphene (SLG) can lead to the formation of optoelectronic devices with enhanced sensitivity and can have extensive applications in the field of the photodetector and photovoltaics. The optical properties of the resultant hybrid material are controlled by the interplay of energy transfer between QDs and charge transfer between the QDs and SLG. By studying the steady-state and time-resolved photoluminescence spectroscopy of hybrid QD-SLG devices, we observe a subtle interplay of short- and long-range energy transfer between cadmium selenide (CdSe) QDs in a compact monolayer solid film placed in close proximity to an SLG and the charge transfer from the QD solid to SLG. At larger separation, I´, between the compact monolayer QD and SLG, the emission properties are dominated by mutual energy transfer between the QDs. At relatively smaller separation the emission from QDs, which is strongly quenched, is dominated by charge transfer between QDs and SLG. In addition, we are also able to tune the relative strength of energy and charge transfer by electrostatic doping through the back gate voltage, which provides a novel pathway to tune emission properties of these devices for possible applications as photodetectors, in photovoltaics, and for sensing. © 2021 American Chemical Society.

Quantum dot nanoparticles (NPs) can be used in several applications, for example, photon upconversion devices that increase the electricity output of solar modules. In order to facilitate life cycle assessment (LCA) studies of such applications, this study provides ready-to-use LCA unit process data for four NPs suitable for photon upconversion applications: cadmium selenide, cadmium sulfide, lead selenide, and lead sulfide. The data is provided for two prospective scenarios: one optimistic and one pessimistic. An impact assessment is conducted in order to assess the NPs’ climate change performance, where solvent-related processes such as steam production for recycling and hazardous waste treatment are shown to be hotspots. To show the applicability of the data, a prospective assessment of a solar module with an upconversion layer is conducted to investigate whether it is preferable from a climate perspective to install more solar modules or equip existing ones with upconversion devices, leading to more electricity produced in both cases. The assessment shows that solar modules need to become 0.05–2 percentage points more efficient per gram of NPs applied, depending on the scenario, in order for the upconversion layer to be preferable.

In the present work Cadmium Selenide (CdSe) and Eu-doped CdSe nanostructures were synthesized by using hydrothermal route. The average crystallite size revealed by powder X-ray studies was found to increase for Eu-doped nanostructures. Morphology study of the Eu-doped CdSe was performed on FESEM and HRTEM. SAED pattern unveiled the crystalline nature of CdSe nanoparticles. UV–Vis absorption studies for the optical band gap was found to be 1.83 eV for CdSe nanoparticles and for Eu3+-doped CdSe it was 1.81 and 1.79 eV, respectively. XPS spectra revealed the presence of prominent cadmium, selenium, and europium peaks for different energy bands. Temperature- and frequency-dependent dielectric studies were performed for the nanostructures. It was observed that ac conductivity increases with the increase in temperature.

Zinc-alloyed cadmium selenide (Cd/ZnSe) quantum dots (QDs) were synthesised in a wet chemical method using thioglycolic acid as a stabilising agent. This facile synthesis method does not require high-temperature or inert gas (argon or nitrogen) atmosphere as required in prevailing methods. Also, this method does not require pyrophoric compounds such as trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO). The synthesised QDs were characterised using a spectrofluorometer, Fourier transform infrared (FT-IR) spectrometer, zeta potential, fluorescence lifetime spectrometer, ICP-OES, and selected area electron diffraction (SAED). The synthesised QDs were spherical with an average diameter of 5.08 nm and has a carboxyl group on their surface making them readily soluble in water and are biologically compatible. The QDs were evaluated for visible light–induced photocatalysis of Rhodamine 6G, and around 68% of the dye was degraded with 60 min of visible light irradiation. The synthesised QDs were tested for its toxicity in Danio rerio embryos including survival percentage, percentage of hatching, heartbeat counts and body length. Based on the toxicity evaluation, along with the presence of the carboxyl group on their surface, these QDs can harbour targeting molecules which will serve as a less toxic molecular imaging probe.

A knowledge of colloidal semiconductor magic-size clusters (MSCs) is essential for understanding how fundamental properties evolve during transformations from individual molecules to semiconductor quantum dots (QDs). Compared to QDs, MSCs display much narrower optical absorption bands; the higher cluster stability gives rise to a narrower size distribution. During the production of binary QDs such as II–VI metal (M) chalcogenide (E) ones, binary ME MSCs observed were interpreted as side products and/or the nuclei of QDs. Prior to the current development of our two-step approach followed by our two-pathway model, it had been extremely challenging to synthesize MSCs as a unique product without the nucleation and growth of QDs. With the two-step approach, we have demonstrated that MSCs can be readily engineered as a sole product at room temperature from a prenucleation stage sample, also called an induction period (IP) sample. It is important that we were able to discover that the evolution of the MSCs follows first-order reaction kinetics behavior. Accordingly, we proposed that a new type of compound, termed as “precursor compounds” (PCs) of MSCs, was produced in an IP sample. Such PCs are optically transparent at the absorption peak positions of their MSC counterparts as well as to longer wavelengths. It is thought that quasi isomerization of a single PC results in the development of one MSC. In this Account, we provide an overview of our latest advances regarding the transformations among binary CdE MSCs as well as from binary CdTe to ternary CdTeSe MSCs. Optical absorption spectroscopy has been employed to study these transformations, all of which display well-defined isosbestic points. We have proposed that these MSC to MSC transformations occur via their corresponding PCs, also called immediate PCs. It is reasonable that the as-synthesized PC (in an IP sample) and the immediate PC (in an incubated and/or diluted sample) probably have different configurations. A transformation between two PCs may involve an intermolecular reaction, with either first-order reaction kinetics or a more complicated time profile. A transformation between one immediate PC and its counterpart MSC may contain an intramolecular reaction. The present Account, which addresses the PC-enabled MSC transformations with isosbestic points probed by optical absorption spectroscopy, calls for more experimental and theoretical attention to understand these magic species and their transformation processes more precisely.

Hypothesis The electrowetting behavior of droplets can be altered by the inclusion of salts, surfactants, or nanoparticles. We propose that varying the properties of cadmium selenide/zinc sulfide quantum dots will affect the electrowetting behavior of fluorescent nanofluids. Information gathered will allow for greater control of fluid properties when designing a colloidal system in an electrowetting environment. Experiments Aqueous-based quantum dots were functionalized with mercaptocarboxylic acid ligands of various chain length and binding motifs by a room temperature phase transfer method. The size and concentration of the quantum dot were varied, and droplets of the resulting nanofluids were exposed to increasing amounts of voltage. The change in contact angle was evaluated and correlated to the surface chemistry, size, and concentration of the quantum dots. Findings Quantum dot nanofluids with longer alkyl chains have the most pronounced change in contact angle and were the most stable under applied voltage. The size of the nanoparticles does not significantly impact the electrowetting behavior at low concentration (3 µM), but nanofluids containing smaller diameter quantum dots show enhanced electrowetting behavior at higher concentration (27 µM). The fluorescent properties of the QD nanofluids studied were not affected after repeated electrowetting cycles.

In order to satisfy the needs for the trace microcystins in water, a novel electrochemiluminescence (ECL) immunosensor was developed based on a dual signal amplification strategy. A MoS2-Au hybrid ...

Size and surface functionality are critically important for organic–inorganic hybrid semiconductive nanocomposites in terms of stable photoelectrochemical properties and superior device performance. The ability of reversible deactivation radical polymerization to control the chain length and dispersity of polymers is herein extended to the tailor-made synthesis of nanocomposites with tunable size, distribution, and surface coating. This is exemplified by the fabrication of cadmium selenide (CdSe) quantum dots (QDs) with uniform sizes from 2 to 10 nm that are intimately coated with poly(3-hexylthiophene) (i.e., CdSe@P3HT).

Cadmium selenide (CdSe) nanostructures with different growth temperature viz. 25 °C, 60 °C, 100 °C, 150 °C and 200 °C have been synthesized through chemical route. The results of XRD reveals that as synthesized CdSe nanostructures possess polycrystalline cubic zinc blende structure. The particle sizes obtained from Scherer formula as well as W-H plot and are found to be 2.81 nm and 4.6 nm respectively. The strain induced in the crystal is obtained as −1.8 × 10−3 from the W-H plot. The results of UV–Vis and photoluminescence (PL) spectra show that growth temperature has a significant impact on the optical properties of the synthesized nanoparticles. Both the UV and PL spectra initially show a blue shift with the increase of temperature but after a particular temperature around 100 °C it starts showing red shift. The PL intensity also increases and possesses a maximum at growth temperature 100 °C but afterwards it again decreases at very high temperatures. From the observation of absorption, PL emission along with intensity it has been inferred that growth temperature ranging from 25 °C to 100 °C may be a suitable technique to modulate the optical properties of chemically synthesized CdSe nanoparticles.

Nanoparticles of cadmium selenide (CdSe) and zinc selenide (ZnSe) have been successfully synthesized by chemical co-precipitation and hydrothermal method. Mercaptoethanol (C2H6OS), and hydrazine hydrate (N2H4) were used as a capping agent to control the size of the nanoparticles (NPs). The structural, UV-optical, morphological studies have been characterized with the help of PXRD, UV, FT-IR, Micro-Raman, HR-TEM and EDAX studies. PXRD is used to calculate the average particle size are found to be ∼1–2 nm for CdSe and ∼16 nm for ZnSe nanoparticles, which have zinc blende phase having cubic structure. HR-TEM images showed that both the samples were agglomerated in spherical shape. Moreover, the presence of functional groups and longitudinal phonon mode were studied by FT-IR and Raman spectral analyzer. Additionally, the optical band gap (Eg) values of CdSe and ZnSe NPs were investigated with the help of UV–Visible diffuse reflectance spectroscopy found to be ∼2.1 eV and ∼2.6 eV, respectively. Further, photocatalytic dye degradation of methylene blue (MB) measured by mixtures of CdSe and ZnSe NPs under 8 W Argon lamp of UV-light irradiation.

A quaternary segmented flow regime for robust and flexible continuous biphasic chemical processes is introduced and characterized for stability and dynamic properties through over 1500 automatically conducted experiments. The flow format is then used for the continuous flow ligand exchange of cadmium selenide quantum dots under high intensity ultraviolet illumination for improved photoluminescence quantum yield.

Quantum dots (QDs) were suggested a decade ago as a means of spectral decoy to divert rocket attacks from flying objects such as satellites but have not yet found industrial applications. A possible reason is that these advanced nanomaterials are unstable in the long-Term under the forces exhibited on a flying object and the nanoparticles might agglomerate to form larger microparticles, which have a different, unwanted spectral footprint. This work proposes an on-board (in situ) real-Time synthesis of quantum dots on a satellite as a result of an interdisciplinary innovation that combines nanomaterial chemistry, heating and mixing with batch microfluidics, and microfabrication of a miniaturized chip. We employed a microchip as the in situ reaction chamber due to its capability of fast, compact synthesis. The implementation of the space micro-reactor, on the other hand, leads to other fundamental challenges that need to be solved such as robust pump-free fluid motion and quick synthesis of quantum dots in less than 180 s which is equivalent to the typical time a rocket needs to reach the satellite from the ground. Additionally, quantum dots need to be tailored in the type of material and size to replicate the spectral signal of the to-be-protected space asset while the synthesis process needs to be robust and resilient to work reliably and automatically under the demanding conditions of a flying object. In this study, we selected cadmium selenide (CdSe) and lead selenide (PbSe) as the materials of choice. Our synthesis process aims to simplify and tailor CdSe and PbSe quantum dots to match the above demands. The produced quantum dots were characterized by their wavelength emission spectra and high-Angle annular dark-field scanning transmission electron microscopy (HAADF STEM) images. Results show that both CdSe and PbSe quantum dots have been successfully synthesized within a maximum of 10 minutes. While the chosen CdSe-based synthesis was unable to reach IR-emitting sizes within several minutes, we managed to meet all other research targets. The synthesized PbSe QDs were able to reach the mock-spectrum and could produce an emission wavelength peak from 1200 to 1400 nm. This work finally provides insights into the limits of batch synthesis in a microfabricated nanodot chip, such as the need to improve reproducibility and enhance particle growth. Based on this learning, we propose a self-priming flow microchip synthesis that can capitalize on mixing as a key asset to overcome those limits.

We report here a rapid visible-light-induced radical polymerization in aqueous media photoinitiated by only ppm level thiol ligand capped cadmium selenide (CdSe) quantum dots (QDs). Simple ligand exchange procedures with various bifunctional thiol ligands facilitate the dispersion of CdSe QDs in water, thus expanding the scope of aqueous photocatalysts. The polymerization showcased excellent oxygen tolerance, giving a low dispersity (Đ) of 1.27. Additive thiol molecules were proposed to act as the coinitiating species, oxidized by photoexcited CdSe QDs to form thiyl radicals and further initiate the polymerization. More importantly, successful thiol–ene click reactions were achieved by scaling up the thiol to olefin ratio to 1, suggesting the thiol ligand coinitiating mechanism and meanwhile demonstrating the great potential of QD photocatalysts in organic transformations. Furthermore, the photoinitiation system using CdSe QDs could be readily employed for photo 3D printing of photocurable resin poly(ethylene glycol) diacrylates, opening up vast opportunities for fabricating advanced polymer–inorganic hybrid materials.

The direct covalent attachment of conducting polymers (CP) to nanoparticles (NP) to form CP-NP nanohybrids is of great interest for optoelectronic device applications. Hybrids formed by covalently anchoring CP to NP, rather than traditional blending or bilayer approaches, is highly desirable. CP-NP nanohybrids have increased interfacial surface area between the two components, facilitating rapid exciton diffusion at the p–n heterojunction. These materials take advantage of the facile solution processability, lightweight characteristics, flexibility, and mechanical strength associated with CPs, and the broad spectral absorption, photostability, and high charge carrier mobility of NPs. We demonstrate the ability to polymerize a hole transporting (HT) polymer utilizing reversible-addition–fragmentation chain transfer (RAFT) polymerization and its subsequent rapid aminolysis to yield a thiol-terminated HT polymer. Subsequent facile attachment to gold (Au) and silver (Ag) NPs and cadmium selenide (CdSe) quantu...

Cadmium selenide (CdSe) quantum dots (QDs) were biosynthesized rapidly in 18 h in Bacillus licheniformis ATCC 11946 (B. licheniformis); this process benefited from the cellular machinery of bacteria metal metabolism, in which inorganic Na2 SeO3 and CdCl2 were chosen as raw materials to produce high quality CdSe QDs by a designed two-step protocol. Research outcomes demonstrated that the purified CdSe QDs possessed maximum fluorescence intensities at weak alkalinity solutions and had good fluorescence stabilities at 4°C as well as at room temperature after standing for 1 week. Glutathione (GSH) concentration and superoxide dismutase (SOD) content, both of which were reported to be greatly related to biosynthetic activities in some bacterial matrices, were monitored during the biosynthetic process in B. licheniformis. Bacterial resistance research further showed that the change in rates in bacterial inhibition zone diameter to seven different antibiotics was less than 9% after B. licheniformis was used to manufacture CdSe QDs, showing a relative lower environmental risk in short-term heavy metal exposure.

Nanocrystalline CdSe films on a frosted glass substrate are synthesized via hydrochemical deposition with sodium selenosulfate using an additive of 5 × 10–4–10–3 mol/L copper(II) chloride. It is found that introducing copper(II) chloride into the reaction mixture accelerates the formation of solid phase CdSe and thins the cadmium selenide layer from 240 to 130–160 nm. It is established that doping with copper does not affect the cubic B3 structure (space group $$F\bar {4}3m$$ ) of the CdSe film, but 10−3 mol/L copper(II) chloride in the reactor reduces the period of the crystal lattice from 0.59967 to 0.59899 nm, due to the formation of supersaturated substitutional solid solution CuxCd1−xSe (x = 0.03). The band gap of the CdSe film, calculated according to light transmittance and diffuse reflectance, is 1.8 eV. Adding copper to the film lowers Еg to 1.6 eV. It is shown that doping with copper results in luminescence in the near-IR spectral range (680–780 nm) and changes conductivity from the n to the p type.

Feeding cadmium (II) and selenium (IV) simultaneously to anaerobic granular sludge with the aim of synthesizing cadmium selenide (CdSe) nanoparticles induces compositional changes in the extracellular polymeric substances (EPS) matrix of this sludge. A methanogenic anaerobic granular sludge was repeatedly exposed to Cd(II) (10–50 mg L−1) and selenite (79 mg L−1) for 300 days at pH 7.3 and 30 °C in a fed-batch feeding regime for enrichment of Se-reducing bacteria and synthesis of CdSe nanoparticles. EPS fingerprints of the granular sludge, obtained by size exclusion chromatography coupled to a fluorescence detector, showed a significant increase in the intensity of protein-like substances with > 100 kDa apparent molecular weight (aMW) upon repeated exposure to Cd(II) and Se(VI). This was accompanied by a prominent decrease in protein-like substances of aMW

Transient supramolecular self-assembly has evolved as a tool to create temporally programmable smart materials. Yet, so far single-component self-assembly has been mostly explored. In contrast, multicomponent self-assembly provides an opportunity to create unique nanostructures exhibiting complex functional outcomes, newer and different than individual components. Even two-component can result in multiple organizations, such as self-sorted domains or co-assembled heterostructures, can occur, thus making it highly complex to predict and reversibly modulate these microstructures. In this study, we attempted to create active bicomponent nanoparticle assemblies of orthogonally pH-responsive-group-functionalized gold and cadmium selenide nanoparticles with temporal microstructural control on their composition (self-sorted or co-assembly) in order to harvest their emergent transient photocatalytic activity by coupling to temporal changes in pH. Moving towards multicomponent systems can deliver next level control in terms of structural and functional outcomes of supramolecular systems.

In this study, a new configuration of dye sensitized solar cells (DSSCs), in which a TiO2 photoanode is co-sensitized by N719 organic dye and CdSe quantum dots (CdSe-QDs), was fabricated. The photovoltaic performance of the cell, which was co-sensitized with an optimum concentration of CdSe-QDs, was found to be superior to that of the cell with a photoanode sensitized using N719 dye. The superior performance can be attributed to the energy-compatible band structures of the N719 dye molecule and the CdSe-QDs, selective transfer of a significant number of photogenerated electrons from the energy state of the dye molecule to the conduction band (CB) of CdSe-QDs, and improved absorbance of the CdSe-QDs in the visible-light spectrum. This initial inflow of electrons to the dye was found to enrich the subsequent dye-mediated electron transfer to TiO2, thus contributing to the enhanced photocurrent in the DSSC. The novel material implemented in this study was based on CdSe-QDs, which were used as a co-sensitizer in the photoanode of the DSSC synthesized by pulsed laser ablation in liquid (PLAL). Morphological, structural, elemental, optical and electrochemical characterizations of the photoanodic materials were conducted; and the photovoltaic characteristics of the fabricated cell were determined. The photovoltaic conversion efficiency of the cell co-sensitized by CdSe-QDs at a certain concentration (1 mg/15 ml of ethanol) and N719 dye was found to be 7.09%, which corresponds to a 37% enhancement of the photovoltaic efficiency when compared with the cell sensitized only by the N719 dye.

We report the rational design and fabrication of magnetically separable zinc ferrite@titanium dioxide (ZnFe2O4@TiO2) hollow core/shell nanospheres as photocatalysts for efficient H2 evolution by loading the TiO2 shell layer on the prepared ZnFe2O4 hollow nanospheres using the kinetics-controlled coating method. Meanwhile, the incident light absorption, photogenerated charge transfer and separation and photocatalytic hydrogen evolution activity were remarkably improved by well anchoring cadmium selenide (CdSe) quantum dots on the ZnFe2O4@TiO2 hollow core/shell nanospheres. This unique design integrates the structural and functional merits of the ZnFe2O4, TiO2, and CdSe quantum dots into porous hollow nanospheres with the double-shell heterostructure. This design significantly accelerates the separation and transport of photogenerated charge carriers, enhances the light absorption, and offers more active sites for the photocatalytic H2 evolution reaction. Benefitting from the unique structural and component merits, the optimized magnetically separable ZnFe2O4@TiO2/CdSe hollow core/shell nanospheres exhibit excellent photocatalytic hydrogen evolution performance with a high H2 generation rate (266.0 μmol h−1·g−1) and high stability.

Measurements of mass attenuation coefficients and X-ray absorption fine structure (XAFS) of zinc selenide (ZnSe) are reported to accuracies typically better than 0.13%. The high accuracy of the results presented here is due to our successful implementation of the X-ray extended range technique, a relatively new methodology, which can be set up on most synchrotron X-ray beamlines. 561 attenuation coefficients were recorded in the energy range 6.8–15 keV with measurements concentrated at the zinc and selenium pre-edge, near-edge and fine-structure absorption edge regions. This accuracy yielded detailed nanostructural analysis of room-temperature ZnSe with full uncertainty propagation. Bond lengths, accurate to 0.003 Å to 0.009 Å, or 0.1% to 0.3%, are plausible and physical. Small variation from a crystalline structure suggests local dynamic motion beyond that of a standard crystal lattice, noting that XAFS is sensitive to dynamic correlated motion. The results obtained in this work are the most accurate to date with comparisons with theoretically determined values of the attenuation showing discrepancies from literature theory of up to 4%, motivating further investigation into the origin of such discrepancies.

Nanoparticle of cadmium selenide (CdSe) was carried out through the green synthesis route method with the help of sodium selenite and cadmium nitrate. To control the size of nanoparticles, the capping agent utilized was starch. X-ray diffraction technique and transmission electron microscopy were used to calculate the grain size as well as the crystal structure of the particles was determined. The optical absorption spectra were studied by the UV–Visible spectroscopy. The morphology of prepared CdSe nanoparticles was studied by scanning electron microscope and TEM. The Fourier infrared spectroscopy (FTIR) was also carried out showing some dominant absorption peaks attributed to the characteristic absorption. The PL excitation spectra showed a single peak at 458 nm and broad PL emission band is visible at 677 nm in the emission spectra. Dielectric studies were carried out for the pelletized sample of CdSe nanoparticles in which the variation of the dielectric constant and dielectric loss were studied. This was done over the lower frequency range to higher frequency range at room temperature and other higher temperatures. The synthesized CdSe showed high dielectric constants at low frequency which rapidly decreases with the increase in the frequency. The dielectric loss also showed similar behavior with small difference. The semiconducting property of CdSe was confirmed, as with the increase of temperature the ac conductivity was also found to be increased.

In the present investigation, the performance of highly sensitive photodetector based on CdSe thin film has been demonstrated. The cadmium selenide (CdSe) films were deposited successfully by spray pyrolysis method on glass substrate. The as-deposited films were used as visible light detector. Further, the structural, morphological, and optical properties of CdSe films were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy, and optical absorption spectrophotometer. The XRD studies show that the produced samples are polycrystalline in nature. A UV–Visible absorbance spectrum indicates direct allowed transition with bandgap about 1.75 eV. The SEM micrographs depict uniformly distributed well defined uneven hexagonal grains. The CdSe film-based photodetector exhibits high responsivity, detectivity and shows an ultrafast photoresponse. The excellent photoresponse and high photosensitivity of CdSe film makes it a strong candidate for high-performance photodetectors.

Because of their lower toxicity, indium phosphide (InP) quantum dots (QDs) are replacing cadmium selenide QDs in applications that require narrowband luminescence across the visible spectrum. Howev...

Early and highly accurate detection of diverse diseases is in urgent demand than ever, especially for cancers and infectious ones. Among possibilities, biosensing by utilizing conjugated nanoparticles is still a method of choice. However, the toxicity of quantum dots remains a big matter of concern in those biooriented applications. In this study, mercaptosuccinic acid-coated cadmium selenide quantum dots of approximately 2.3 nm were synthesized with a simple green method at low temperature and cost-saving chemicals. The influence of synthesis factors was investigated with different spectroscopic methods. The toxicity issue was evaluated on the NIH-3T3 cell line (ATCC® CRL-1658™) and an MTT assay, revealing a secure threshold of 20 μg/ml. Consequently, successful conjugation to the CD3 antibody including an A/G protein bridge was implemented and verified with fluorescent methods. Finally, Jurkat T cell detectability of conjugated CdSe was successfully validated with fluorescent microscopy. The CdSe-based products are accessible for future biosensing applications.

Three-monolayer CdSe nanoplatelets having the composition (CdSe)3[Cd(OAc)0.77(oleate)1.23]0.78, large lateral dimensions, minimal strain distortions, and the zinc-blende crystal structure undergo Z...

We report on the colloidal stability of nanoparticles with alkanethiol shells in apolar solvents. Small-angle X-ray scattering and molecular dynamics simulations were used to characterize the interaction between nanoparticles in linear alkane solvents ranging from hexane to hexadecane, including 4 nm gold cores with hexadecanethiol shells and 6 nm cadmium selenide cores with octadecanethiol shells. We find that the agglomeration is enthalpically driven and that, contrary to what one would expect from classical colloid theory, the temperature at which the particles agglomerate increases with increasing solvent chain length. We demonstrate that the inverted trend correlates with the temperatures at which the ligands order in the different solvents and show that the inversion is due to a combination of enthalpic and entropic effects that enhance the stability of the ordered ligand state as the solvent length increases. We also explain why cyclohexane is a better solvent than hexadecane despite the two having very similar solvation parameters.

Upconversion photodetectors convert photons from the infrared to the visible light spectrum and are of use in applications such as infrared detection and imaging. High-performance upconversion devices are, however, typically based on vacuum-deposited materials, which are expensive and require high operating voltages, which limits their implementation in flexible systems. Here we report solution-processed optical upconversion photodetectors with a high photon-to-photon conversion efficiency of 6.5% and a low turn-on voltage of 2.5 V. Our devices consist of a colloidal lead sulfide quantum dot layer for harvesting infrared light that is monolithically coupled to a cadmium selenide/zinc selenide quantum dot layer for visible-light emission. We optimized the charge-extraction layers in these devices by incorporating silver nanoparticles into the electron transport layers to enable carrier tunnelling. Our photodetectors exhibit a low dark current, high detectivity (6.4 × 1012 Jones) and millisecond response time, and are compatible with flexible substrates. We also show that the devices can be used for in vitro bioimaging. By embedding silver nanoparticles in the electron transport layer, solution-processed quantum-dot-based photodetectors with a high photon-to-electron conversion efficiency of 6.5% and a low turn-on voltage of 2.5 V can be created for use in infrared imaging applications.

The mobility of charge carriers across a semiconductor nanoparticle based 3D network (i.e. a gel) and the interfacial transfer of the charge carriers across the nanoparticle network/electrolyte boundary are elementary processes for applications in the fields of sensing and energy harvesting. The automated manufacturing of electrodes coated with porous networks can already be realized by inkjet printing. By simultaneous printing of CdSe/CdS dot-in-rod shaped nanorods (NRs) and the destabilization reagent, CdSe/CdS gel network coated electrodes can be obtained. In the presented work, the charge carrier mobility of the electrons and the holes within the porous CdSe/CdS nanorod gel network are investigated via photoelectrochemistry. Under application of linear sweep voltammograms (LSVs) and intensity modulated photocurrent spectra (IMPS) it is shown, that the electron is moving within the tip-to-tip connected CdSe/CdS NR gel structure, while the holes are trapped in the CdSe seed of the semiconductor heterostructures. Furthermore, the preparation process of gel structures is related to the elementary mechanism of hydration, which can be shown via photoelectrochemical long term studies.

In recent years, microwave heating techniques for quantum dot (QD) synthesis have come to supplement the typical hot-injection methods. In addition to increasing control and replicability, microwave synthesis can be up-scaled to industry standards, an advantage that increases its lucrativeness. This study depicts a strategy to take a hot-injection procedure for cadmium selenide (CdSe) QD synthesis that is safe enough for undergraduate research labs and adapt it to an easier, more energy-efficient microwave synthesis method. Additionally, this study details successes in synthesizing these QDs, along with some challenges, limitations, and peculiarities. For future users of this method, it is recommended to keep holding temperatures between 170°C and 240°C to achieve the highest monodispersity of CdSe QDs while also avoiding confounding effects, such as wide-spectrum photoluminescence and bulk CdSe precipitation.

In this article, the influence of structural and phase changes on the thermoelectric properties of PbTe doped with CdSe compounds of various molar concentrations were studied. The research showed that with a minimum value of the lattice parameter of the formed new phases in the PbTe matrix (at an impurity concentration of 0.5 mol%), the specific electrical conductivity and thermoEMF coefficient have a minimum value. A further increase in concentration leads to an increase in these parameters.

In the present report, thin films of Cadmium Selenide (CdSe) and Zn doped Cadmium Selenide (CdSe:Zn) have been deposited on Fluorine doped tin oxide coated (SnO 2 :F) glass substrate by electrodeposition technique. Structural investigation showed that the prepared films have polycrystalline nature with cadmoseleite structure. Williamson Hall plot analysis has been used to estimate the microstructural parameters. Film composition has been analyzed using Energy dispersive X-ray analysis. UV–Visible spectroscopic measurement has been carried out to find out the parameters such as Band gap, refractive index, extinction coefficient value of the deposited films.

Photoelectrode plays significant role in excitonic solar cells i.e., (i) as an acceptor and (ii) transport media of excited state electron from the fluorophore upon absorption of energy of photon; which prevents from electron-hole recombination in the fluorophore. The evolution of opto-electronic properties of the ZnO upon change of size, however, receives insufficient attention from researchers. Therefore, the aim of this paper is to establish few realistic clusters of (ZnO)n (n = 3, 6, 12, 13, and 21) to study their opto-electronic properties using quantum chemical calculations at the level of B3LYP functional and lanl2dz basis set. Geometry of the clusters were optimized to the lowest energy structures; evaluated as realistic using a combination of harmonic frequency calculations, and experimental works. A device structure of cadmium selenide-based solar cell was used in the study to analyze the energy level alignment, and compatibility of the ZnO realistic clusters.

A computer model of nonradiative electronic excitation energy transfer from nanoclusters of colloidal quantum dots of cadmium selenide to the meso-tetra(3-pyridyl)porphyrin molecule in hybrid nanostructures nanocluster–dye has been constructed and analyzed. The model uses the experimental luminescence and absorption spectra of quantum dots and the dye, takes into account heterogeneity of the properties of quantum dots in nanoclusters and the different location of the dye in the hybrid structure. It has been shown that, in the ideal case, due to such energy transfer, the intensity of the luminescent signal of the dye can be increased by five orders of magnitude. However, this value is significantly reduced due to nonluminescent particles, the presence of a protective ligand shell, a large size distribution of the particles, and the nonoptimal geometric structure of the hybrid system.