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Polyyne bridges have attracted extensive interest as molecular wires due to their shallow distance dependence during charge transfer. Here, we investigate whether triplet energy transfer from cadmium selenide (CdSe) quantum dots (QDs) to anthracene acceptors benefits from the high conductance associated with polyyne bridges, especially from the potential cumulene character in their excited states. Introducing π-electron rich oligoyne bridges between the surface-bound anthracene-based transmitter ligands, we explore the triplet energy transfer rate between the CdSe QDs and anthracene core. Our femtosecond transient absorption results reveal that a rate constant damping coefficient of β is 0.118 ± 0.011 Å−1, attributed to a through-bond coupling mechanism facilitated by conjugation among the anthracene core, the oligoyne bridges, and the COO⊖ anchoring group. In addition, oligoyne bridges lower the T1 energy level of the anthracene-based transmitters, enabling efficient triplet energy transfer from trapped excitons in CdSe QDs. Density-functional theory calculations suggest a slight cumulene character in these oligoyne bridges during triplet energy transfer, with diminished bond length alternation. This work demonstrates the potential of oligoyne bridges in mediating long-distance energy transfer. [ABSTRACT FROM AUTHOR]

Combining a molecular thiomolybdate cluster, [Mo3S13]2−, with cadmium selenide quantum dots capped with tetraethyleneglycol monomethyl ether phosphonate (TEGPA) ligands results in a highly active photocatalytic system for the production of hydrogen under visible light irradiation. The system reaches turnover numbers exceeding 30 000 and remains active for ∼200 h. [ABSTRACT FROM AUTHOR]

In this thorough study, the examination explores the Rayleigh-type surface wave propagation in an imperfectly bonded layered structure. The present study adopts the conceptual framework of the Green–Naghdi model type III of hyperbolic thermoelasticity. This approach allows for an in-depth exploration of the interactions and properties of the system, offering valuable insights into how these arrangements behave within the scope of thermoelastic phenomena. The process of deriving the secular equations for Rayleigh-type surface waves are accomplished in this study. Four distinct secular equations are derived corresponding to different boundary conditions. In this article, plane harmonic wave solutions are used to determine the mechanical displacement, electrical potential for the layer, and the mechanical displacement, electrical potential, and temperature change for the half-space. The effects on various wave properties, including phase velocity, attenuation coefficient, and specific loss, are shown graphically within the framework of the GN-III type model with cadmium selenide (CdSe) and PZT-5H material. This mathematical framework may be useful for a variety of scientific and engineering disciplines that involve the implementation of sensors, actuators, capacitors, electrostatic transducers, and applications for surface acoustic wave devices and Rayleigh-type wave sensors. [ABSTRACT FROM AUTHOR]

Optoelectronic synaptic devices have been regarded as the key component in constructing neuromorphic computing systems. However, the optoelectronic synapses based on conventional 2D transistor are still suffering low photosensitivity and volatile retention behavior, which can affect the recognition accuracy and long-term memory. Here, a novel optoelectronic synaptic device based on surface-state-rich CdSe nanobelt photosensitized 2D MoS2 transistor is demonstrated. Benefiting from the excellent light absorption of CdSe and effective charge trapping at the hetero-interface, the device exhibits not only high photosensitivity but also long retention time (>1,500 s). In addition, typical synaptic functions including the excitatory postsynaptic current, paired-pulse facilitation, the transformation from short-term to long-term plasticity, the transformation from short-term to long-term plasticity, spike-amplitude-dependent plasticity, and learning-forgetting-relearning process are successfully simulated and modulated by light stimulation. Most importantly, an artificial neural network is simulated based on the optical potentiation and electrical habituation characteristics of the synaptic devices, with recognition accuracy rates of 89.2, 93.8, and 91.9 % for file type datasets, small digits, and large digits are achieved. This study demonstrates a simple and efficient way to fabricate highly photosensitive optoelectronic synapse for artificial neural networks by combining the merits of specific materials and device architecture.

AbstractA nanocomposite (NC) of polycarbonate (PC), poly(methyl methacrylate) (PMMA), polyethylene oxide (PEO) and cadmium selenide (CdSe) nanoparticles (NP) was prepared using thermolysis and ex-situ casting techniques. The microstructure and shape of the CdSe NP were characterized with the Rietveld methodology and transmission electron microscopy (TEM). Rietveld refinement of x-ray data indicated that the prepared CdSe NP had the cubic zinc blend structure with a lattice parameter of 6.057 Å. TEM images showed the formation of a dotted shape of CdSe with a particle size around 2 nm, confirming the quantum dot size of the mother phase CdSe. Samples from the prepared PC/PMMA/PEO/CdSe NC films were irradiated with γ ray doses ranging from 5 to 80 kGy. We used UV-vis spectroscopy to investigate the resultant effects of the γ ray irradiation on the optical properties of the prepared films. The effect of the γ ray irradiation on the light absorbance, extinction coefficient, refractive index and optical conductivity of the PC/PMMA/PEO/CdSe NC films was studied. The absorbance of the NC films increased as they were irradiated with the γ ray doses up to 80 kGy, the maximum dose used. The increase in absorbance was accompanied with a decrease in the direct bandgap, from 5.31 to 4.05 eV, and an increase of Urbach energy from 0.44 to 0.89 eV. Also, we used the optical dielectric loss (ε”) to identify the type of microelectronic transition for the PC/PMMA/PEO/CdSe NC films, which was found to be a direct allowed transition. Furthermore, the optical color changes between the pristine and the irradiated films were evaluated using the International Commission on Illumination (CIE) color differences technique. The pristine film was uncolored. It showed significant color alterations when irradiated with γ radiation up to 80 kGy, the maximum dose used. [ABSTRACT FROM AUTHOR]

Photosensitive quantum dot light‐emitting diodes (PSQLEDs) possess the dual capabilities of generating and detecting light signals, which is of significant importance for the development of miniaturized and integrated optoelectronic devices. However, the state‐of‐the‐art PSQLEDs can only detect light signals within a certain wavelength range, and require switching between the two functions under different bias voltage directions. In this work, The use of a ZnO/quantum dots (QDs)/ZnO multilayer (ZQZ ML) architecture as both the electron transport layer and the photosensitive layer is pioneered. The QDs in this structure are composed of narrow‐bandgap lead sulfide QDs and wide‐bandgap cadmium selenide QDs, successfully realizing a unique PSQLED device with C photosensitive characteristics. As a result, the as‐fabricated device can respond to illumination from 365 to 1300 nm, and the device achieves a photoresponse rate of 20.9 mA W−1 in self‐powered mode to UV light. After UV light irradiation, the maximum external quantum efficiency and maximum luminance of device reached 11.8% and 64,549 cd m−2, respectively. The device shows a record‐high luminance ON/OFF ratio of 5500%, which is beneficial for high contrast and accurate information display. [ABSTRACT FROM AUTHOR]

The nanostructured powders of cadmium selenide semiconductor were prepared hydrothermally using two synthesis protocols, after which they were annealed at 200°C for different times (0, 4, 8, and 12 h). In order to obtain a well-crystalline powders with a stable, single-phase structure of CdSe, and then delve into studying their structural and morphological properties and ensuring that they are completely free of impurities, that is, the presence of only the basic components of Cd and Se, while determining their atomic ratios, as well as explaining the chemical reactions occurring in both protocols, the rate of change on the CdSe nano-powders under the influence of increasing the annealing time was clear and very important until very satisfactory results were given compared to what was obtained from the hydrothermal process alone, that is, without annealing. This required the use of several techniques. The diffractograms of the two CdSe powders after a certain annealing time estimated between 4 and 8 h depending on the protocol of synthesis, showed a crystallization of pure hexagonal structure of the CdSe wurtzite phase with crystallites of nanometric size, approximately 13 nm. [ABSTRACT FROM AUTHOR]

Cadmium selenide (CdSe) represents a direct-bandgap semiconductor belonging to the II–VI group, operating within the visible range of the electromagnetic spectrum. Nanowires composed of CdSe hold significant potential for various optoelectronic applications. Employing ion implantation is an immensely appealing technique, which allows for a controlled introduction of dopants into any lattice, and it is based on well-established principles. In this context, the current investigation focuses on the impact of argon ion implantation on cadmium selenide nanowires with a diameter of 80 nm. The nanowires were synthesized via a template-assisted electrodeposition method using polycarbonate membranes with 80 nm pores and 10 µm thickness. A three-electrode setup facilitated their fabrication. Subsequently, argon ions with a 4+ charge state and an energy of 1 MeV were implanted into the synthesized nanowires at varying fluence levels, ranging from 1011 to 1013 ions/cm2. The ion implantation process was conducted in the radiation chamber of the Inter-University Accelerator Centre's low-energy ion implantation facility in New Delhi, India. Stopping and Range of Ions in Matter (SRIM) code simulations were employed to determine the optimal implantation parameters. Compositional analysis confirmed the successful incorporation of argon ions into the CdSe lattice. Notably, scanning electron microscopy revealed no alterations in the nanowire morphology despite the implantation. X-ray diffraction analysis showed no shift in the 2θ position of diffraction peaks, but indicated variations in their intensities. Furthermore, the implanted nanowires exhibited an increased absorbance and improved conductivity with increasing ion fluence. These findings demonstrate the effectiveness of argon ion implantation in modifying the optical and electrical properties of 80 nm diameter CdSe nanowires. [ABSTRACT FROM AUTHOR]

Optoelectronic synaptic devices have been regarded as the key component in constructing neuromorphic computing systems. However, the optoelectronic synapses based on conventional 2D transistor are still suffering low photosensitivity and volatile retention behavior, which can affect the recognition accuracy and long-term memory. Here, a novel optoelectronic synaptic device based on surface-state-rich CdSe nanobelt photosensitized 2D MoS2 transistor is demonstrated. Benefiting from the excellent light absorption of CdSe and effective charge trapping at the hetero-interface, the device exhibits not only high photosensitivity but also long retention time (>1,500 s). In addition, typical synaptic functions including the excitatory postsynaptic current, paired-pulse facilitation, the transformation from short-term to long-term plasticity, the transformation from short-term to long-term plasticity, spike-amplitude-dependent plasticity, and learning-forgetting-relearning process are successfully simulated and modulated by light stimulation. Most importantly, an artificial neural network is simulated based on the optical potentiation and electrical habituation characteristics of the synaptic devices, with recognition accuracy rates of 89.2, 93.8, and 91.9 % for file type datasets, small digits, and large digits are achieved. This study demonstrates a simple and efficient way to fabricate highly photosensitive optoelectronic synapse for artificial neural networks by combining the merits of specific materials and device architecture. [ABSTRACT FROM AUTHOR]

This study demonstrates effective manipulation of exciton spin dynamics in a prototypical chiral inorganic nanosystem, i.e., cadmium selenide (CdSe) nanosheets capped with chiral cysteine ligands in aqueous solution, via facile pH‐regulation that can directly modify the electronic coupling between CdSe and cysteine's thiol group through Cd─S bonding. The comparative scrutiny by using transient circular dichroism spectroscopy enables to decipher the pertinent mechanisms behind the pH‐regulated spin‐flip dynamics. The hole‐trapping interaction between the valence‐band heavy‐hole spin state of CdSe and the cysteine‐induced "extrinsic" surface state is found to play a dominant role in prolonging the hole spin relaxation lifetime (by more than threefold). This study also demonstrates a relevant application in modulating the sensitivity of circularly polarized light detection. This work sets a paradigm for harnessing the elusive interactions in chiral inorganic nanosystems to achieve desired spin‐polarization regulation, refreshing the fundamental understanding about the mechanisms of spin dynamics involved therein. [ABSTRACT FROM AUTHOR]

The results of molecular dynamics simulation of the crystal structure of the currently most studied CQDs, based on cadmium selenide nanoparticles, are presented, and issues concerning the structure of the ligand shell of these nanoparticles, primarily made of trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO) molecules, which act as a medium and as precursors in the chemical reaction that results in the formation of CQDs, are discussed in detail. [ABSTRACT FROM AUTHOR]

In this work, the photoconductivity (PC) spectrum of thin CdSe films was studied. In the course of studies on glass substrates, thin films of cadmium and selenium with a thickness of h = 200 nm and h = 400 nm were selected. The thickness of the samples obtained by chemical deposition was determined by the gravimetric method. Since CdSe crystal is a light-sensitive semiconductor material, the photoconductivity of thin films has been studied. The spectra obtained during studies carried out at a wavelength λ = 600-1100 nm were analyzed. It has been established that the spectrum is chaotic, since in the h = 200 nm layers the phase is not completely formed. In the layers h = 400 nm, a maximum centered at the wavelength λ = 710 nm was recorded. [ABSTRACT FROM AUTHOR]

We present a comprehensive investigation into the potential of n-type indium-doped cadmium selenide telluride (CST:In) as a high-performance candidate for solar cell applications, without the need for resource-intensive post-growth treatments that are required for CdTe:In. We compared undoped CST and CST:In crystals under different growth conditions, analyzing their structural and electronic properties using x-ray diffraction (XRD), electron probe microanalysis (EPMA), current–voltage (IV) and Hall effect measurements, time-resolved photoluminescence (TRPL), optical transmission, and photoluminescence (PL) mapping. The results reveal that as-grown CST:In crystals achieve nearly 100% carrier activation, yielding an electron concentration of 9.5 × 1018 cm−3, mobility of 653 cm2/V·s and a 5 ns lifetime which approaches the radiative limit. Furthermore, comparison of PL maps from crystal growths having different cooling profiles suggests a strong effect of cooling rate on selenium segregation and cubic/hexagonal/polytype phase distribution. Slower cooling leads to a more homogeneous cubic structure with lower Se segregation, while a faster cooling rate results in increased Se segregation, and twin boundaries and stacking faults with polytypic and hexagonal character. [ABSTRACT FROM AUTHOR]

Liquid crystal (LC) materials exhibit interesting electro-optic switching and molecular ordering properties. Furthermore, the addition of chemically compatible active emitters such as core-shell quantum dots (QD) in a LC medium allows optical as well as dielectric tuning in an anisotropic, reconfigurable ordered medium. Order in a nematic LC phase is characterized by an orientational order parameter. In this work, we demonstrate the use of patterned substrates to generate arrays of integer topological defects in a nematic LC medium doped with cadmium selenide (core) cadmium sulfide (shell) core–shell QDs. We demonstrate the formation of metastable air-pillar-induced integer topological defects (TDs) in relatively thinner 9 μm LC sandwich cells, and the formation of field-induced TDs in thicker (25 μm) cells. Simultaneously, the self-assembly of core-shell QDs into square arrays on the patterned substrates is discussed, highlighting potential electro-optic device applications. The surfactant hexadecyltrimethylammonium bromide (CTAB) is found to play a significant role in LC TD formation as well as QD spatial organization at the optimized concentration. Self-assembly and ordering of single- and multi-component LCs within structured devices is a highly relevant problem for modern optoelectronic devices. This work opens new possibilities for classical as well as quantum light sources which require spatially ordered optical emitters in a reconfigurable dielectric medium at a micron-scale. [ABSTRACT FROM AUTHOR]

Cadmium selenide (CdSe) quantum dots (QDs) with different size, 2.5 and 3.2 nm, were successfully deposited on mesoporous titanium dioxide (TiO2) (Degussa-P25) nanostructures by electrophoretic deposition method (EPD) at the applied voltage 100 V for 120 s deposition time. In this study, the morphology of CdSe films deposited by EPD and the performance of the film when assembled into a solar cell were investigated. From the field emission scanning electron microscopy cross-section, the thickness of the CdSe nanoparticles with size 2.5 nm films were 3.4 and 3.0 μ m for CdSe 3.2 nm nanoparticles film. The structure of 2.5 nm is denser than compare of 3.2 nm CdSe nanoparticles. From UV visible spectroscopy, the band gap calculated for 2.5 nm CdSe nanoparticles is 2.28 eV and for 3.2 nm is 2.12 eV. Photovoltaic characterization was performed under an illumination of 100 mW cm−2. A photovoltaic conversion efficiency of 1.81% was obtained for 2.5 nm CdSe and 2.1% was obtained for 3.2 nm CdSe nanoparticles. This result shows that the photovoltaic efficiency is dependent on CdSe nanoparticle size. [ABSTRACT FROM AUTHOR]

Despite the promising applications of the use of quantum dots (QDs) in the biomedical field, the long-lasting effects of QDs on the cell remain poorly understood. To comprehend the mechanisms underlying the toxic effects of QDs in yeast, we characterized defects associated with receptor-mediated endocytosis (RME) as well as pinocytosis using Saccharomyces cerevisiae as a model in the presence of cadmium selenide/zinc sulfide (CdSe/ZnS) QDs. Our findings revealed that QDs led to an inefficient RME at the early, intermediate, and late stages of endocytic patch maturation at the endocytic site, with the prolonged lifespan of GFP fused yeast fimbrin (Sac6-GFP), a late marker of endocytosis. The transit of FM1-43, a lipophilic dye from the plasma membrane to the vacuole, was severely retarded in the presence of QDs. Finally, QDs caused an accumulation of monomeric red fluorescent protein fused carbamoyl phosphate synthetase 1 (mRFP-Cps1), a vacuolar lumen marker in the vacuole. In summary, the present study provides novel insights into the possible impact of CdSe/ZnS QDs on the endocytic machinery, enabling a deeper comprehension of QD toxicity. [ABSTRACT FROM AUTHOR]

Applying the cohesive energy model, this research theoretically studies how the size of nanoparticles affects their optical characteristics. The findings demonstrate that optical characteristics are size-dependent for nanoparticles, with an exponentially growing energy gap for nanoparticles on a scale of less than 4 nm. As the size of nanoparticles is reduced, the absorption wavelength also decreases. Compounds undergo a transition to a higher energy spectral area (blue shift) when their wavelength decreases; this change can make these compounds effective in certain optical nanodevices. [ABSTRACT FROM AUTHOR]

This study is focused on investigating the atomic dynamics and vibrational properties of thin layers of cadmium selenide with thickness ranging from 200–500 nm. The studies were carried out using Raman spectroscopy at room temperature. Raman spectra were obtained in the frequency range ν = 100-800 cm-1 . Two vibration modes were observed within the specified frequency range. It has been established that these vibration modes correspond to vibrations of Cd–Se covalent bonds. The frequency of these vibrational modes was observed to increase as the thickness of CdSe thin films increased, which was attributed to the formation of a thickness-dependent phase. [ABSTRACT FROM AUTHOR]

Thin films of cadmium selenide with a thickness h = 200-500 nm were obtained and their surface properties were studied. The studies were carried out using a Scanning Electron Microscope. It was found that with increasing thickness of thin layers, the surface structure becomes smoother. A compositional analysis of the surface of thin layers was also carried out. Elemental analysis was carried out in layers of various thicknesses, the percentage content of chemical elements and the energy spectrum of chemical elements were determined. It has been established that thin CdSe films obtained by chemical deposition are quite pure. The surface of thin layers with a thickness h > 400 nm turned out to be quite smooth, which is an indicator of the formation of a phase in these layers corresponding to the CdSe compound. [ABSTRACT FROM AUTHOR]

Tailoring the electronic, optical, and transport properties of low-dimensional semiconductor materials is essential to improve the light-conversion efficiency of thin-film solar cell materials. Here, using first-principles calculations and non-equilibrium Green functions, we investigate the enhancement of optoelectronic and transport properties of armchair graphene nanoribbons (AGNRs) upon adsorption of cadmium selenide clusters. Upon adsorption of a CdSe diatomic molecule on an AGNR, the most energetically favorable configuration is the cadmium end sitting on top of a carbon atom. The corresponding electronic bandgap reduces ∼5 times with respect to that of the pristine system, thanks to the formation of a polaron state formed by the p-orbital of the selenide atom. Upon adsorption of CdSe cyclohexane molecules, the bandgap of this system slightly shrinks by 0.121 eV with respect to the pristine system. The charge accumulation induced by these clusters significantly enhances the absorption coefficient of the adsorbed systems, resulting in a red shift of the optical spectra toward the infrared region. More interestingly, by solving the Bethe–Salpeter equations with the Tamm–Dancoff approximation, we provide a direct link between the first-principles optical prediction and experimental observations. In addition, the electron transfer from these molecules to the hosted systems increases the transmission spectra in the vicinity of the Fermi level, leading to a remarkable electronic current passing through these scattering regions. These results highlight the role of cadmium selenide clusters in enhancing the light-to-energy conversion efficiency of next-generation solar cell devices. [ABSTRACT FROM AUTHOR]

Even with significant developments in nanoscience, relatively little is known about the interactions of nanocrystal semiconducting materials with bio-macromolecules. To investigate the interfacial phenomena of cadmium selenide quantum dot (CdSe QD) nanocrystals with proteins extracted from Moringa oleifera seeds, different concentrations of cadmium selenide quantum dots–Moringa oleifera seed protein (CdSe–MSP) complexes were prepared. Respective CdSe QDs with hexagonal phase and crystalline size in the range of 4–7 nm were synthesized and labelled with the purified mesoporous MSP having a surface area of 8.4 m2/g. The interaction mechanism between CdSe QDs and MSP was studied using UV–Vis absorption, fluorescence emission and Fourier Transform Infrared spectroscopies. The UV–Vis absorption spectra showed absorption bands of CdSe–MSP complexes at 546.5 nm. The fluorescence intensity of CdSe QDs was found to decrease with increasing concentration of MSP. The thermodynamic potentials ∆ H θ (−321.3 ×   10 3 Jmol−1);   ∆ S θ (156.0 JK−1mol−1) and ∆ G θ (−46.6 ×   10 3 Jmol−1) were also calculated. The stability of the complex found is strongly influenced by electrostatics interaction and surface-bound complexation equilibrium attraction. This information can help to elucidate the surface characteristics of MSP and its potential interactions with other molecules or nanoparticles. [ABSTRACT FROM AUTHOR]

Cadmium mercury selenide (CdHgSe) nanocrystals exhibit a unique combination of low‐energy optical absorption and emission, which can be tuned from the visible to the infrared range through both quantum confinement and adjustment of their composition. Owing to this advantage, such nanocrystals have been studied as a promising narrow‐band infrared light emitter. However, the electroluminescence of CdHgSe‐based nanocrystals has remained largely unexplored, despite their potential for emitting light in the telecom wavelength range. Further benefits to their optical properties are expected from their shape control, in particular the formation of 2D nanocrystals, as well as from a proper design of their heterostructures. In this work, a colloidal synthesis of CdHgSe/ZnCdS core/shell nanoplatelets (NPLs) starting from CdSe template NPLs employing a cation exchange strategy is developed. The heterostructures synthesized exhibit photoluminescence that can be tuned from ≈1300 to 1500 nm. These near‐infrared‐active NPLs are employed in light‐emitting diodes, demonstrating low turn‐on voltage and high external quantum efficiency. [ABSTRACT FROM AUTHOR]

Thin films of antimony-doped cadmium selenide (CdSe/Sb) were fabricated using the spray pyrolysis technique on both glass and fluorine tin oxide (FTO) substrates at a deposition temperature of 200ºC. Sodium selenosulphite (Na2SeSo3) served as a stable source of Se2- ions, and to ensure complete desolation and achieve ion-by-ion deposition, Ethylenediamine tetraacetic acid (EDTA) was employed as a stabilizer and complexing agent. Antimony and cadmium were sourced from their respective chlorides. The optical and solid-state properties were determined through absorption and transmittance measurements in the wavelength range of 300 to 1500 nm. A comparison of the spectral properties between films deposited on glass and FTO substrates revealed distinct characteristics. Films on glass exhibited a continuous spectral nature, while those on FTO displayed a quantized energy level characteristic with a lower band gap ranging between 2.65 to 2.80 eV. In contrast, films on glass substrates demonstrated a higher band gap in the range of 3.7 eV to 4.0 eV. The observed lower band gap and quantized energy levels in films on FTO substrates suggest their suitability for photovoltaic applications by enhancing the absorption of a broader range of solar radiation. In contrast, films on glass with a higher band gap are more suitable for applications requiring selective light absorption or filtering, such as solar thermal collectors or windows, enabling control over specific wavelengths while maintaining transparency. The ability to adjust the band gap through film deposition conditions allows tailored material optimization for diverse solar technologies, impacting efficiency, and manufacturing costs based on specific requirements and considerations. [ABSTRACT FROM AUTHOR]

Context: The thermoelectric properties of cadmium selenide (CdnSen) molecular junctions (n = 7, 11, 13) were investigated before and after adding hydrogen atoms. The effects of hydrogen passivation on the transmission and thermopower curves were analyzed. CdSe-diamantane (Cd7Se7) and CdSe-tetramantane (Cd11Se11) junctions exhibited the best thermoelectric performance due to their low surface reconstruction energy, which is attributed to the number of dangling and unsaturated bonds. This study guides the design of new molecular junctions with desired thermoelectric properties. Method: The electrical and thermal properties of cadmium selenide (CdnSen) molecular junctions (n = 7, 11, 13) were investigated using a ballistic quantum transport method based on the non-equilibrium Green's function (NEGF) approach. Thermoelectric properties were calculated for the molecular junctions with different structures before and after hydrogen passivation. Density functional theory (DFT) calculations were performed at the B3LYP level with the 3-21G basis set for the Cd atoms and the 6-31G** basis set for the Se atoms. The SIESTA and GOLLUM codes were used to study the effect of changing the shape and size of each structure on its electrical and thermal characteristics. [ABSTRACT FROM AUTHOR]

In this work, thin films of cadmium selenide of difrent thicknesses were obtained by chemical deposition and the processes of phase formation in them were studied. Thin layers with a thickness of d = 150 -- 500 nm were obtained. Structural studies were carried out using X-ray diffraction. The spectra obtained at room temperature were analyzed. The presence of structural features of the CdSe compound in thin layers has been established. After a thickness d = 400 nm, the process of phase formation begins. The observed atomic planes and Miller indices during the phase formation process are determined. [ABSTRACT FROM AUTHOR]

We have studied the optical and luminescence properties at room temperature of ultrathin colloidal semiconductor cadmium selenide nanoscrolls with a thickness of 2.5 monolayers. For colloidal synthesis of the objects under study, cadmium acetate dihydrate Cd(CH3COO)2·2H2O and trioctylphosphine selenide were used as precursors of cadmium and selenium, respectively, and solutions of oleic acid and octadecene were also used. Luminescence spectrum of cadmium selenide nanoscrolls was recorded using a fiber charge coupled device spectrometer. Spectrally resolved photoluminescence decays for nanoparticles were measured with the use of time-correlated single photon counting technique. The emission of the cadmium selenide nanoscrolls consists of interband and recombination luminescence bands. We found that the normalized photon numbers of recombination luminescence are larger than the normalized photon numbers of interband luminescence. We determined dominant wavelengths, chromaticity coordinates, and correlated color temperatures of ultrathin colloidal semiconductor cadmium selenide nanoscrolls. These ultrathin cadmium selenide nanoscrolls are promising for application in light-emitting diodes.

In this work, cadmium selenide quantum dots (CdSe QDs)-doped polymer stabilized cholesteric liquid crystals composites (PSCLC) are proposed for low-power light shutters. CdSe QDs with different concentrations, (0.1 and 0.25 wt.%) into PSCLC composites are fabricated and studied. The phase-dependent and morphological studies are investigated in all the samples. The morphological study reveals that doped sample transform from planar to homeotropic type of orientation at low voltage (~15 V), at an optimum concentration 0.1 wt. % of CdSe QDs in PSCLC. Dielectric analysis infers that dispersion of CdSe QDs increases the permittivity (~36%) of the composites. At 0.1 wt.% QDs-doped PSCLC system, the dielectric anisotropy also increases, however a decrease in splay elastic constant could be seen. Voltage dependence on transmission behaviour also shows that the threshold as well as saturation voltages are lower (6.5 V and 19.5 V, respectively) for 0.1 wt.% QDs-doped system than undoped sample. This signifies that desired alignment to the liquid crystal molecules is easily achieved at low electrical energy by the incorporation of CdSe QDs. CdSe QDs may be incorporated into PSCLC to develop novel functional devices operated at low power. Polymer-stabilized cholesteric liquid crystal (PSCLC) with varying concentrations of cadmium selenide quantum dots (CdSe QDs) has been prepared and investigated in thin sample cells. Dispersion of CdSe QDs doped PSCLC samples increases the dielectric permittivity by 36%. Reduction in threshold and saturation voltages is achieved at an optimum concentration of 0.1 wt.% CdSe QDs in PSCLC. With an optimised value of CdSe QDs into PSCLC, low-power consumption-based light shutter may be fabricated. [ABSTRACT FROM AUTHOR]

In this work, cadmium selenide (CdSe) thin films were deposited successfully by spray pyrolysis at different substrate temperatures. The influence of the preparation technique on the optical, morphological, and structural properties of the different substrate temperature CdSe films were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Visible optical transmission. The XRD analysis reveals that CdSe thin film has hexagonal (wurtzite) and (cubic) crystal structures with different particle sizes depending on the substrate temperature. The SEM image shows uniform and adherent crystals. The optical energy gap was found to be in the range of 1. 70 - 2.59 eV with different temperatures. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) have been highly sought after in the past few decades for their potential to be used in many biomedical applications. However, QDs' cytotoxicity is still a major concern that limits the incorporation of QDs into cutting-edge technologies. Thus, it is important to study and understand the mechanism by which QDs exert their toxicity. Although many studies have explored the cytotoxicity of quantum dots through the transcriptomic level and reactive species generation, the impact of quantum dots on the expression of cellular protein remains unclear. Using Saccharomyces cerevisiae as a model organism, we studied the effect of cadmium selenide zinc sulfide quantum dots (CdSe/ZnS QDs) on the proteomic profile of budding yeast cells. We found a total of 280 differentially expressed proteins after 6 h of CdSe/ZnS QDs treatment. Among these, 187 proteins were upregulated, and 93 proteins were downregulated. The majority of upregulated proteins were found to be associated with transcription/RNA processing, intracellular trafficking, and ribosome biogenesis. On the other hand, many of the downregulated proteins are associated with cellular metabolic pathways and mitochondrial components. Through this study, the cytotoxicity of CdSe/ZnS QDs on the proteomic level was revealed, providing a more well-rounded knowledge of QDs' toxicity. [ABSTRACT FROM AUTHOR]

This contemporary work delineates the photocatalytic and antibacterial activity of titanium (Ti) and lanthanum (La)‐doped cadmium selenide (CdSe) nanoparticles produced by a simple wet chemical method. Studies using diffraction and microscopy reveal that the synthesized samples devised cubic crystalline structure. The incorporation of the dopant into the host material is analyzed using X‐ray diffraction, scanning electron microscope–EDAX, and transmission electron microscopic studies. The photocatalytic activity Ti‐ and La‐doped CdSe nanoparticles results in improved degradation toward methylene blue (MB) dye under direct solar irradiation. This unique behavior is ascribed to the enhanced light absorption tendency with larger charge separation efficiency. Ongoing operational factors like initial dye concentration, catalyst dose, pH, and duration are evaluated regarding their effects on MB dye degradation. The photocatalytic activity for MB follows pseudo‐first‐order kinetics. The antibacterial activity of Ti– and La–metal‐doped CdSe is tested against Pseudomonas arueginosa and Staph aureus bacteria. The Ti–CdSe and La–CdSe nanoparticles show good antibacterial activity after 24 h of bacterial growth Pseudomonas arueginosa and Staph aureus, respectively. Based on the findings, Ti–CdSe and La–CdSe nanoparticles exhibit an enhanced photocatalytic and antibacterial activity when compared with CdSe nanoparticles. [ABSTRACT FROM AUTHOR]

Luminescence and colorimetric properties of ultrathin two-dimensional CdSe nanostructures rolled into scrolls 2.5 monolayers thick are studied. It is shown that photoluminescence of samples under study is caused by interband transitions which corresponds to the violet region of the visible spectrum, and transitions involving surface states, which corresponds to the almost entire optical range. The relaxation dynamics of the excited states corresponding to these transitions was studied. The chromaticity coordinates and dominant wavelengths are calculated for ultrathin CdSe nanoscrolls. The colorimetric characteristics of nanoparticles under study are analyzed in comparison with thicker nanoscrolls and quasi-two-dimensional CdSe nanocrystals from the literature sources. [ABSTRACT FROM AUTHOR]

CdSe quantum dots stabilized with oleic acid were obtained by the colloidal method and their optical properties were studied. The average nanoparticle size, determined by the exciton absorption peak, was 3.7 nm. By growing a ZnS shell onto the surface of CdSe nanoparticles, CdSe/ZnS core-shell hybrids are synthesized. In this case, the quantum yield of luminescence increases from 19 to 76%. It was shown that during the growth process, the size of the CdSe core decreases to 2.8 nm due to the replacement of surface cadmium ions by zinc ions. As a result, the absorption and emission peaks of CdSe/ZnS quantum dots shift to the short-wavelength region. The total (hydrodynamic) particle size increases due to formation of the ZnS shell. The obtained nanoparticles are used in surface modification reactions by replacing the stabilizer. For efficient replacement molecules containing a terminal thiol group were selected – dodecanethiol-1 and dihydrolipoic acid dodecyl ester, capable of forming strong bonds with the surface of the nanoparticles. Ligand exchange reactions were carried out under mild conditions using an excess amount of a thiol stabilizer. Successful replacement of the stabilizers was established by IR spectroscopy. It was also determined that some of the oleic acid molecules remain unsubstituted. It is shown that surface modification leads to a change in the hydrodynamic size of quantum dots, due to the difference in the lengths of the molecules used in the reactions. The optical properties of modified quantum dots were investigated. It was found that the attachment of thiol stabilizers to the surface leads to a decrease in their luminescence intensity. [ABSTRACT FROM AUTHOR]

Increasing photon absorption by capturing light is an important way to increase the efficiency of photovoltaic devices. In this regard, the small optical band gap (Eg) and high absorption coefficient of Se-containing thin nanofilms make them ideal for next generation photovoltaic devices based on selenides. Amorphous selenium was introduced into polyamide-6 (PA 6) via a chemical synthesis in a bath and the influence of the products of its reaction with Cd2+ and Ag+ ions on the film phase composition, topographic and optical properties were evaluated. AFM data have revealed that the surface roughness of the a-Se/PA 6 composite noticeably increases compared to that of unreacted PA 6. However, at later stages of film deposition, the roughness decreases, and the thin film becomes smoother and uniform. The incorporation of solid inorganic nanoparticles into flexible polyamide network causes chain stretching, which has been confirmed by ATR-FTIR spectroscopy data. The data of X-ray diffraction analysis, depending on the stage of synthesis, showed the crystalline composition of the film with peaks of Se8, CdSe, Ag2Se and Ag, which may explain the observed optical properties. The optical properties of the composites indicate a shift in the band gap from 4.46 eV for PA 6 to 2.23–1.64 eV upon the stepwise deposition of amorphous Se, CdSe and Ag2Se. Eg is conveniently located in the visible region of solar energy, making the obtained nanofilms ideal for solar energy harvesting. [ABSTRACT FROM AUTHOR]

Present studies demonstrate the dispersion effect of cadmium selenide quantum dots on ferroelectric liquid crystal mixture properties. Varying concentrations of cadmium selenide quantum dots (0.05 wt.%, 0.10 wt.% and 0.50 wt.%) have been taken to investigate its influence on the physical parameters of ferroelectric liquid crystal mixture KCFLC 10R. Phase transition, textural, electro-optical and photoluminescence studies have been performed in planar aligned cells. The presence of QDs disturbs the geometrical symmetry and molecular tilt of ferroelectric liquid crystal molecules which results in the modification of physical parameters of ferroelectric liquid crystal. It has been observed that doped samples have shown decrement in spontaneous polarisation and rotational viscosity. However, there is an improvement in the response time of the doped samples. The reduction in the spontaneous polarisation with voltage signifies that doped samples can operate at low voltage (~6 V) as compared to ferroelectric liquid crystal mixture (~12 V). Photoluminescence studies reveal that all the samples absorb UV light ~340 nm and produce visible emission at ~ 400 nm which can behave as UV light storage and high contrast display. This would be beneficial for luminescent displays as well as UV to visible light conversion applications. Dispersion of cadmium selenide quantum dots with varying concentration in ferroelectric liquid crystal mixture has been investigated. Temperature- as well as voltage-dependent electro-optical parameters and photoluminescence studies have been done and analysed. Fast response time has been observed in the doped samples as compared to FLC mixture. Doped samples can be operated at low voltage (~6 V) as compared to FLC mixture (~12 V) These prepared samples can be used for UV to visible light conversion applications. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting has attracted significant attention as a low-cost, clean, and green method for the conversion of solar energy into hydrogen, highlighting its potential to solve energy and environmental problems. In this work, we report the coupling of a plasmonic resonator with semiconductor quantum dots (QDs) for enhancement in photoelectrocatalytic water splitting toward hydrogen (H2) production. Specifically, cadmium selenide (CdSe) QDs were deposited on silver nano-gratings (Ag gratings). Plasmonic enhancement was observed in the absorption/emission of QDs using our angle-resolved steady-state optical spectroscopy. Furthermore, angle-resolved absorption spectra helped us to optimize the illumination conditions for resonant excitation using a setup for photoelectrochemical (PEC) experiments. Under the resonant pump, the emission of the QDs has been plasmonically enhanced with a Purcell factor ( F P ) of ∼1.5. Our numerical simulation revealed a strong near-field enhancement due to the excitation of surface plasmon resonances, contributing to F P . A similar enhancement order in the PEC experiments was also observed under resonant pump conditions, indicating the contribution of plasmon resonances to the enhanced photoelectrocatalysis. Switching the excitation's polarization further reinforces this, resulting in an enhanced photocurrent under p-polarization. These findings provide a proof of concept, thus laying the foundation for a practical device for efficient solar-to-H2 conversion. [ABSTRACT FROM AUTHOR]

The effect of a nontoxic chloride treatment on the crystallinity and optoelectrical characteristics of a CdSe thin film was studied. A detailed comparative analysis was conducted utilizing four molarities (0.01 M, 0.10 M, 0.15 M, and 0.20 M) of indium (III) chloride (InCl3), where the results showed a notable improvement in CdSe properties. The crystallite size of treated CdSe samples increased from 31.845 nm to 38.819 nm, and the strain in treated films dropped from 4.9 × 10−3 to 4.0 × 10−3, according to XRD measurements. The highest crystallinity resulted from the 0.10 M InCl3-treated CdSe films. The In contents in the prepared samples were verified by compositional analysis, and FESEM images from treated CdSe thin films demonstrated compact and optimal grain arrangements with passivated grain boundaries, which are required for the development of a robust operational solar cell. The UV-Vis plot, similarly, showed that the samples were darkened after treatment and the band gap of 1.7 eV for the as-grown samples fell to roughly 1.5 eV. Furthermore, the Hall effect results suggested that the carrier concentration increased by one order of magnitude for samples treated with 0.10 M of InCl3, but the resistivity remained in the order of 103 ohm/cm2, suggesting that the indium treatment had no considerable effect on resistivity. Hence, despite the deficit in the optical results, samples treated at 0.10 M InCl3 showed promising characteristics as well as the viability of treatment with 0.10 M InCl3 as an alternative to standard CdCl2 treatment. [ABSTRACT FROM AUTHOR]

Thermal evaporation was used to prepare nickel (Ni) doped cadmium selenide thin films in different proportions (0, 1 and 3) wt.% on glass substrates at room temperature. According to XRD examination, all films possessed a polycrystalline hexagonal structure, with the (002) plane as the ideal orientation. According to AFM analysis, the average particle size decreases as the amount of doping increases, showing that the distribution of grains has become more uniform. The transmission and distortion ratios of the films were measured to learn more about their optical properties, which revealed that the (CdSe) films' transmittance decreased as the Ni films were doped, respectively. Additionally, it was discovered that all produced films had absorption coefficients larger than (a >104 - 1) and that the value of this coefficient rises with increasing doping. The films exhibited all direct optical energy gaps, according to the findings (CdSe). As the doping fraction decreased, the gap values decreased from 1.72 eV to 1.62 eV. [ABSTRACT FROM AUTHOR]

This article presents a demonstration of the significant impact that the atomic masses of constituent atoms and the isotopically pure and heavy property of a constituent atom have on the thermal conductivity in the zinc blende crystal structure of semiconductor materials. We take boron arsenide and gallium arsenide from the semiconductors of groups (iii - v) as well as cadmium selenide and cadmium telluride from the semiconductors of groups (ii - vi) . Thermal conductivity is acquired by using the first-principles calculation technique and the Boltzmann transport equation with the relaxation time approximation. The corresponding thermal conductivity of CdSe and CdTe are 7.58 Wm - 1 K - 1 and 5.27 Wm - 1 K - 1 at room temperature (300 K) , which is significantly lower than that of BAs. We performed calculations of phonon scattering, group velocities, relaxation time, mean free path, and the mode Grüneisen parameter to investigate such differences in their thermal characteristics. The outcomes of our research have the potential to enhance our understanding of the mechanisms of heat transfer in BAs, CdSe, CdTe, and GaAs, and to validate the criteria for identifying semiconductor materials with high thermal conductivity, thereby enabling the design of more efficient nano-electronics. [ABSTRACT FROM AUTHOR]

The electrodeposition from room temperature ionic liquids (RTILs) has recently come up as a low-cost technique for the growth of II–VI semiconductor compounds and thin films, some promising alternatives to classical organic or inorganic solvents. As a relatively new field of study, only a few reports exist describing the growth mechanism of electrodeposition from RTILs, especially for CdSe films. In this paper, a new electrochemical method has been developed for the deposition of Cadmium Selenide thin layers onto indium doped tin oxide coated conducting glass (ITO) using an RTIL and an Organic solvent system (Tricaprylmethylammonium chloride/Formamide). Structural properties of prepared films have been investigated by X-ray diffraction (XRD) and micro-Raman analysis which reveal a pure cubic phase with the zinc-blende-type structure and typical peaks of nanostructured CdSe, respectively. Atomic force microscopy (AFM) analysis showed homogenous and smooth surface of the deposited films. UV-vis measurements demonstrated the presence of direct transition with a band gap energy around 1.68 eV. The flat-band potential and carrier density values of CdSe thin film are − 0.667 V and 6. 1 3 × 1 0 1 6 cm − 3 , respectively, as deduced from Mott–Schottky studies. The photoelectrochemical (PEC) behavior of the CdSe thin film exhibited an enhanced photocurrent density at about 0.35 mA/cm2 vs. Ag/AgCl. [ABSTRACT FROM AUTHOR]

The present study describes the synthesis of CdSe-incorporated TiO2 nanotubes (CdSe@TNT) via a modified hydrothermal method from CdSe-incorporated spherical TiO2 (CdSe@sTiO2). The structural and photocatalytic activities of both composites are then compared with spherical TiO2 (sTiO2). Quantum dots of CdSe are synthesized by varying Cd:Se precursor ratios and were incorporated into the TiO2 nanotubes (CdSe@TNT) hydrothermally. It is observed that the ratio of Cd:Se used for forming CdSe quantum dots is directly related to the band gap of CdSe@TNT. Reduction in the band gap of TiO2 was confirmed using UV–Vis DRS spectroscopy, and the band gap energy was evaluated to be 3.02 eV, 2.94 eV and 2.89 eV for sTiO2, CdSe@sTiO2 and CdSe@TNT, respectively. XPS peaks reveal elemental peaks of Cd and Se in the TiO2 nanostructure, confirming the formation of the composite. The micro Raman spectroscopy and XRD analysis revealed that structure of TiO2 becomes strained due to incorporation of CdSe in TiO2. The average crystalline sizes of sTiO2, CdSe@sTiO2 and CdSe@TNT are 5.28 nm, 4.36 nm and 2.43 nm, respectively. The morphology of the CdSe@TNT was investigated by HR-TEM. The redesigned interface of heterostructures is further investigated by carrying out the electrochemical properties, and it was observed that the CdSe@TNT heterostructures had a better electrical conductivity. Photocurrent response (I-t) curves for sTiO2, CdSe@sTiO2 and CdSe@TNT reveal that after five cycles, a maximum photocurrent value of 0.0363, 0.0970 and 0.1144 mA cm−2 for sTiO2, CdSe@sTiO2 and CdSe@TNT, respectively, was observed. The photocatalytic efficiency of the synthesized nanomaterial was further investigated using methylene blue dye as a model compound. [ABSTRACT FROM AUTHOR]

CdSe Quantum dots (QDs) are cytotoxic cadmium and selenide-based (II–VI) semiconductor nanocrystals with a few nanometer diameters and unique optical and electrical properties. The cytotoxicity of CdSe QDs should not be underestimated and has raised considerable concern. That toxicity is mostly determined by the surface characteristics and size of the particles. The core/shell configuration thus becomes a popular technique to modify the activity of quantum dots by enhancing biocompatibility and stability. The most common and effective synthesis method of those shell-free and core/shell-based CdSe QDs is organometallic and water-based synthesis. Those synthesis frequently requires high temperatures, an oxygen-free atmosphere, and highly poisonous substances like trioctylphosphane (TOP) or trioctylphosphane oxide (TOPO), which may be inefficient, harmful to the environment, and even deadly. Because of this, a biogenic synthesis method was made to get around its limits. Biosynthesis of quantum dots by microorganisms (bacteria, actinomycetes, fungus, and algae) is an environmentally friendly and cost-effective green technology where production may occur intracellularly or extracellularly. The enzyme NADH-dependent nitrate reductase has been reported to have an important role in reducing cadmium and selenide ions to CdSe QDs by several researchers. When synthesizing CdSe QDs, factors such as pH, temperature, synthesizing route, and substrate concentration affect the final product's size and form. They have attracted interest because of their potential usage in a wide range of applications, including photovoltaics, solar cells, LEDs, photocatalyst, optical sensors, medical, medicines, and optical amplifiers. In this review, we focus on the cytotoxicity of non-shell and core/shell-based CdSe QDs, the synthesis using a consortium of different microorganisms from both prokaryotes and eukaryotes, affecting factors, application, challenges, and future prospects of CdSe-based QDs. [ABSTRACT FROM AUTHOR]

Erbium-doped cadmium selenide thin films grown on 7059 Corning glass by means of a chemical bath at 80 °C were prepared. Doping was performed by adding an aqueous Er(NO3)33·H2O dilution to the CdSe growth solution. The volume of Er doping solution was varied to obtain different Er concentration (x at%). Thus, in the Cd1−xErxSe samples, the x values obtained were in the 0.0–7.8 at% interval. The set of the CdSe:Er thin films synthesized in the hexagonal wurtzite (WZ) crystalline phase are characterized by lattice parameters (a and c) that increase until x = 2.4% and that subsequently decrease as the concentration of x increases. Therefore, in the primitive unit cell volume (UC), the same effect was observed. Physical parameters such as nanocrystal size, direct band gap (Eg), and optical longitudinal vibrational phonon on the other hand, shift in an opposite way to that of UC as a function of x. All the samples exhibit photoluminescence (PL) emission which consists of a single broad band in the 1.3 ≤ hν ≤ 2.5 eV range (954 ≥ λ ≥ 496 nm), where the maximum of the PL-band shift depends on x in the same way as the former parameters. The PL band intensity shows a singular behavior since it increases as x augments but exhibits a strong decreasing trend in the intermediate region of the x range. Dark d.c. conductivity experiences a high increase with the lower x value, however, it gradually decreases as x increases, which suggests that the Er3+ ions are not only located in Cd2+ sites, but also in interstitial sites and at the surface. Different physical properties are correlated among them and discussed considering information from similar reports in the literature. [ABSTRACT FROM AUTHOR]

The effect of the type of doping (surface (I) or bulk (II) doping) on the character of the dipole plasmon mode in semiconductor CdSe nanocrystals has been studied. It was found that in case I (donors located on the surface of the nanocrystal) the collective mode had a rotational character and only the angular degrees of freedom were excited. On the contrary, in case II the charge of the dopant impurities was distributed throughout the system and plasmon excitation was the oscillation of delocalized charge carriers in the direction normal to the surface. It was shown that the position of the resonance line was determined not only by the concentration of free charges, but also by the character of their collective motion determining by the type of doping.

This study elucidates the propagation of surface (Rayleigh type) waves in a homogeneous, transversely isotropic, piezothermoelastic half-space subjected to stress free, electrically open or shorted, and thermally insulated or isothermal boundary conditions, based on GN-III type and three-phase-lag thermoelastic models. Plane harmonic wave solutions are employed to find the mechanical displacements, electrical potential, and temperature change. With the aid of these expressions, stresses, electrical displacement, and temperature gradient are derived. Based on different boundary conditions, four secular equations are derived in the considered half-space. Path of the surface particles traces an elliptic path in vertical plane parallel to the direction of wave propagation and the eccentricity of the ellipse is calculated. Particle path degenerates a straight line when there is no phase difference between vertical and horizontal components of displacements. A pre-established analysis is discussed as a particular case of this study. Effect of various characteristics of waves like phase velocity, attenuation coefficient, and specific loss is demonstrated graphically for the GN-III type and three-phase-lag thermoelastic models engaging cadmium selenide (6 mm class) material of hexagonal symmetry. This mathematical framework may be utilized to design and develop temperature sensors, and other piezoelectric surface acoustic wave (SAW) devices. [ABSTRACT FROM AUTHOR]