ZnSe Quantum Dots Research Articles

Zebrafish imaging and two-photon fluorescence imaging using ZnSe quantum dots* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61774062 and U20A20206), the Science and Techology Program of Guangzhou City, China (Grant No. 2019050001), and the Natural Science Foundation of Guangdong Province, China (Grant Nos. 2018A030313854 and 2016A030308010).

This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility, which can be used in bioimaging. Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation. These biocompatible quantum dots exhibit a two-photon cross-section of 9.1 × 105 GM (1 GM = 10−50 cm4⋅s/photon). Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not co-cultured with quantum dots. After incubating zebrafish larvae with ZnSe quantum dots for 24 h, the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group. The proposed material shows a great potential application in biological imaging.

Effect of dipole–dipole interactions on the one-photon and two-photon photoluminescence in an ensemble of quantum dots doped in a polymer matrix

We have developed a theory for the one-photon and two-photon fluorescence of a nanohybrid composite comprised of an ensemble of quantum dots encased in a matrix of polymer. The quantum dots are comprised of four-level quantum emitters encased within a coating of dielectric material. The fluorescence of the quantum dot system is calculated using the master equation method where dipole–dipole interaction (DDI) coupling is present. The application of a probe field to the nanohybrid composite material in conjunction with the DDI between the quantum dots generates an enhancement of both the single-photon and double-photon fluorescence, and in certain conditions causes spectrum splitting. With a strong DDI field, the two-photon emission spectrum experiences slight quenching and shifts from one peak to two peaks. The dressed states are a result of strong coupling effects between the DDI field and the quantum dots. We generated an analytical expression for the fluorescence spectrum and intensity, and quantitatively compared it to experimental data in which ZnSe quantum dots were embedded within a P3HT polymer film, with our theory strongly correlating with the experiment. We also quantitatively compared our theory with experimental data that demonstrated the single-photon emission spectrum of colloidal quantum dots comprised of a CdZnS/ZnS gradient structure in varying probe field strengths. We found that our theory predicted the spectrum peak splitting that the experiment produced.

Synthesis of photoactivated highly fluorescent Mn2+-doped ZnSe quantum dots as effective lead sensor in drinking water

In this work, manganese doped zinc selenide (Mn@ZnSe) quantum dots (QDs) were prepared via a direct aqueous route. The X-ray diffraction pattern reveals the crystalline cubic zinc blende structure of QDs. With Mn2+ doping, a new high-intensity orange photoluminescence (PL) band centered at around 580 nm obtained owing to 4T1 → 6A1 of Mn2+ ion transitions (for orange QLEDs). The freshly prepared water-dispersible QDs were treated under the UV-radiation for the photoactivation process, which enhanced the PL quantum efficiency from 5 % to 17.3 %. The response of QDs towards different metals was recorded in terms of absorption, PL and PL-lifetime. Among the numerous metals, Pb2+ shows strong PL quenching and the corresponding Stern-Volmer plot showed linearity with the detection limits of 29.8 × 10−6 M in ultrapure water. The developed Mn@ZnSe QDs could act as a non-toxic sensor to sense hazardous lead in drinking water.

Fluorescent reversible regulation of cysteamine-capped ZnSe quantum dots successively induced by photoinduced electron transfer of herring sperm DNA and intercalation binding of ethidium bromide

A fluorescent reversible regulation was studied by fluorescence spectra, ultraviolet–visible spectra in the combination of molecular docking, which based on the photoinduced electron transfer(PET) from hsDNA (herring sperm DNA) to CA (cysteamine)-capped ZnSe QDs (quantum dots) and intercalation of ethidium bromide (EB) into hsDNA. It was proven that the QDs bound with the adding hsDNA by electrostatic force and formed 1:1 hsDNA-QDs complexes, leading to the PET from hsDNA to QDs, and consequently the fluorescence quenching of the QDs; with EB being added in the complex solution, it bound with hsDNA by intercalation interaction and caused hsDNA releasing from hsDNA-QDs complex with forming 2.5:1 EB-hsDNA complex, leading to the recovery of fluorescence, based on the greater binding constant (1.74 × 106 L·mol−1) of hsDNA with the embedded EB comparing to that of QDs with the captured hsDNA (4.25 × 104 L·mol−1). A good linear relationship existed between the fluorescence recovery yield and the EB concentrations under the range of 1.0—12.0 × 10−6 mol·L−1 with bare interference of related substances. This work provided some useful insights into the study of binding mechanism between DNAs with their intercalators and fluorescence bi-direction regulation, and showed great potential for the determination of trace EB.

Novel synthesis of Mn: ZnSe@ZnS core–shell quantum dots based on photoinduced fluorescence enhancement

A novel Type-I Mn: ZnSe@ZnS core–shell quantum dots (QDs) was reported through a two-step procedure by using low-cost inorganic salts and naturalbiomacromolecule as raw materials. Based on a designed structure of L-cysteine-capped Mn: ZnSe QDs in aqueous media with the controllable surface, Mn: ZnSe@ZnS core–shell QDs were formed due to photoactive ions and defect curing under continuous constant light. The influences of experimental variables, including synthesis conditions of Mn: ZnSe QDs, different types and affecting factors of photo irradiation had been systematically investigated. Under the effect of photoinduced fluorescence enhancement, the photoluminescence (PL) intensity increases significantly by about 5–10 times after 1–3 h of UV irradiation. The position of the fluorescence peak was red-shifted by about 17 nm, emitting orange-red fluorescence. The photoluminescence quantum yield (PL QY) was markedly improved (up to 35%). The structure and morphology of Mn: ZnSe@ZnS core–shell QDs were also confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) in detail. The mechanism of photoinduced fluorescence enhancement was attributed to L-cysteine allowed to release S2- to form a ZnS shell, and the passivated surface non-radiative relaxation centers of Mn: ZnSe@ZnS QDs was successfully synthesized with highuniform size, excellent photoluminescence performance, and good stability, all ofwhichmakethemgood potential candidates for white LEDs, and biological labels.

Growth and properties of hydrothermally derived crystalline ZnSe quantum dots.

Chalcogenide nanostructures are the materials with diverse applications. Here, we report rapid hydrothermal synthesis of crystalline ZnSe quantum dots (QDs), avoiding the use of toxic chemicals. To the best of our knowledge, this is the first report on very rapid (5h) hydrothermal synthesis of pristine ZnSe QDs. Elemental selenium is used as a source for selenium. Structural, morphological, compositional, and optical properties of the semiconductor were studied. Structural properties (X-ray diffraction) demonstrate that the particles have grown in a single cubic phase. Morphological studies show formation of agglomerated QDs (4nm). The material possess stoichiometric ratio of the constituent elements that are uniformly distributed. Selected area electron diffraction (SAED) study indicated the material is polycrystalline in nature. Optical properties demonstrated that the QDs are suitable for optoelectronic devices exhibiting room temperature photoluminescence. Commission Internationale de l'Éclairage (CIE) chromaticity diagram shows the material exhibits violet emission and hence suitable for violet LEDs that have potential ability in clinical applications.

Enhancing the Photovoltaic Performance of Solid-State Dye-Sensitized Solar Cells with Composite Materials and Luminescent Down-Shifting

Dye-sensitized solar cells produce saturation of electrons and holes when exposed to high-intensity UV photons. These photon energies do not match the bandgap of the semiconductor materials, which not only degrades the dye and electrolyte but also disrupts the electron kinetics. In this work, graphene oxide (GO) was incorporated into TiO2 to form a composite photoanode structure. The results indicated that a composite photoanode based on GO/TiO2 enhanced the power conversion efficiency of a solid-state dye-sensitized solar cell (ss-DSSC) by 62% compared to that of pure TiO2. This enhancement is attributed to the high conductivity of graphene oxide. Further improvement in device performance was obtained by plasmonic luminescent down-shifting (LDS), where the UV region of the solar spectrum is shifted hundreds of nanometers. The multifunctional LDS coating layer was fabricated with a composite of ZnSe quantum dots and Ag nanoparticles. The experimental results demonstrated the ability of LDS to absorb photons at wavelengths below 400 nm and re-emit them at longer wavelengths (above 400 nm), where the cell has better photovoltaic response. When compared to a bare ss-DSSC, the power conversion efficiency (PCE) is enhanced by 37.62% for cells with a Ag/ZnSe coating layer. Moreover, the LDS-coated device exhibits 16.45% increased photon-to-current conversion efficiency compared to the LDS-free device for wavelengths lower than 500 nm. The 240-h aging tests confirmed that the LDS-coated ss-DSSC retained ∼ 83% of its original PCE value. This potential LDS coating layer not only leads to excellent device stability but also improves the cell performance, which increases the market value of the ss-DSSCs.

Synthesis of starch-g-poly (acrylic acid)/ZnSe quantum dot nanocomposite hydrogel, for effective dye adsorption and photocatalytic degradation: thermodynamic and kinetic studies

Quantum dot nanocomposite hydrogels have received much attention for designing highly efficient photocatalyst due to the stability of the quantum dots in the hydrogel network. In this study, ZnSe quantum dot nanocomposite hydrogel (ZnSe QD-NCH) was prepared based on starch and acrylic acid as an effective dye adsorbent and photocatalyst by free radical polymerization and subsequent loading of zinc and selenide ions. The structure of ZnSe QD-NCH was confirmed by various techniques, such as, Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, transmission electron microscopy, and fluorescence analysis. The effects of various parameters on crystal violet (CV) adsorption were examined, including temperature, contact time, pH, initial dye concentration, and the amount of adsorbent. The best adsorption was obtained at 65 °C, 30 min, pH = 6, C0 = 10 ppm, and 0.05 g dose of adsorbent. The photocatalytic activity of ZnSe QD-NCH was investigated in the presence of visible and ultraviolet light. The results demonstrated that removal of dye by ZnSe QD-NCH is 94.5%, 95.5%, and 98.5% in dark, visible, and UV light, respectively. The kinetic studies showed that dye adsorption follows the pseudo second-order kinetic model. The isotherm models of dye adsorption demonstrated that the adsorption behavior follows the Freundlich isotherm model. The negative Gibbs free energy also indicated that removal of CV is spontaneous. The reusability experiments showed that the adsorption of CV is more than 89% after 4 cycles.

The constructive role of ZnSe passivating layer on the photovoltaic performance of the fast-fabricated CdS/CdSe quantum dot sensitized solar cells

In this research CdS and CdSe co-sensitized quantum dot sensitized solar cells were fabricated and the photovoltaic (PV) performance was improved. CdS quantum dots (QDs) layer was deposited on nanocrystalline TiO2 scaffold through the conventional successive ionic layer adsorption and reaction (SILAR) method. The CdSe nanocrystals film was also over-coated by an improved, fast and effective chemical bath deposition (CBD) approach. The power conversion efficiency was quite increased by application of a ZnSe passivating layer. This electron blocking layer could reduce the back-recombination rate of electrons with the electrolyte. That is while the photo-created holes are not blocked and could be well-transported based on the corresponding flat-band energy diagram of the fabricated device. The ZnSe over-layer was formed through a controlled SILAR process while the Se source was quite protected under the Ar gas flow during the deposition. Different number of SILAR cycles was applied for the ZnSe film formation and photovoltaic characteristics were investigated. The results demonstrated that the optimized cell with a ZnSe passivation layer deposited in three specific SILAR cycles represented a Jsc of 17.7 mA/cm2, Voc of 594 mV, FF of 0.5 and maximum power conversion efficiency of 5.3%. This efficiency was enhanced about 70% compared to that of the reference cell which was not passivated with ZnSe QDs layer.

Single-Precursor Intermediate Shelling Enables Bright, Narrow Line Width InAs/InZnP-Based QD Emitters

Bright, narrow spectrum infrared emitters, particularly Cd- and Pb-free materials, are of interest for bioimaging, photodetection, and telecommunications. InAs-based quantum dots (QDs) are promising emitters in this spectral range; however, efforts to increase the photoluminescence quantum yield (PLQY) tend to broaden the PL line width as a consequence of interfacial defect formation when thick shells, lattice-mismatched with the core, are employed. Here we report that developing a single-precursor complex for InZnP growth enables uniform shell growth that maintains the excellent size dispersion (6%) of the cores. The introduction of this intermediate layer is key to facilitate the subsequent growth of different shells to improve radiative recombination without sacrificing size uniformity. The growth of InAs/InZnP/ZnSe leads to a PL full-width at half-maximum (fwhm) of 100 meV at 1.12 eV with a PLQY of 14%. We then further introduce an additional GaP layer to increase the radiative/nonradiative relative rate. InAs/InZnP/GaP/ZnSe QDs reach a PLQY of 23% while maintaining a narrow fwhm.

Photoinduced charge carrier dynamics in a ZnSe quantum dot-attached CdTe system.

A new nanohybrid material is prepared by attaching CdTe nanoneedles (NNs) to surface-modified ZnSe quantum dots (QDs). The NNs and QDs are prepared by a colloidal synthesis method in an aqueous alkaline medium. The surface modification and the attachment of nanostructures are achieved by a bifunctional ligand 3-mercaptopropionic acid (3-MPA). The band gap of the ZnSe QDs is varied by controlling the size of the QDs in order to get the maximum overlap between the absorption band of the CdTe NNs and the emission band of the ZnSe QDs, which is a prerequisite for effective charge/energy transfer. The possibility of photoinduced charge transfer (PCT) and Förster resonance energy transfer (FRET) from the donor (QDs) to the acceptor (NNs) has been assessed. Very fast (less than 800 ps) PCT and FRET from QDs to NNs occur because the emission band of QDs overlaps with the absorption band of NNs. The calculated large value of the overlapping integral, J(λ) ∼4.5 × 1019 M-1 cm-1 nm4, of the donor and the acceptor bands proves the feasibility of energy transfer. These findings suggest that the ZnSe QDs can exchange photoinduced energy with the CdTe NNs effectively over a wide distance in a CdTe-ZnSe nanohybrid.

Surface and intrinsic contributions to extinction properties of ZnSe quantum dots

This work studies extinction properties of ZnSe quantum dots terminated with either Se-surface or Zn-surface (Se-ZnSe or Zn-ZnSe QDs). In addition to commonly observed photoluminescence quenching by anionic surface sites, Se-ZnSe QDs are found to show drastic signatures of Se-surface states in their UV-visible (Vis) absorption spectra. Similar to most QDs reported in literature, monodisperse Zn-ZnSe QDs show sharp absorption features and blue-shifted yet steep absorption edge respect to the bulk bandgap. However, for monodisperse Se-ZnSe QDs, all absorption features are smeared and a low-energy tail is identified to extend to an energy window below the bulk ZnSe bandgap. Along increasing their size, a cyclic growth of ZnSe QDs switches their surface from Zn-terminated to Se-terminated ones, which confirms that the specific absorption signatures are reproducibly repeated between those of two types of the QDs. Though the extinction coefficients per unit of Se-ZnSe QDs are always larger than those of Zn-ZnSe QDs with the same size, both of them approach the same bulk limit. In addition to contribution of the lattice, extinction coefficients per nanocrystal of Zn-ZnSe QDs show an exponential term against their sizes, which is expected for quantum-confinement enhancement of electron-hole wavefunction overlapping. For Se-ZnSe QDs, there is the third term identified for their extinction coefficients per nanocrystal, which is proportional to the square of size of the QDs and consistent with surface contribution.

Detection of three tumor biomarkers in human lung cancer serum using single particle inductively coupled plasma mass spectrometry combined with magnetic immunoassay

A new method for simultaneously determining cytokeratin fragment antigen 21–1 (CYFRA21-1), carcinoembryonic antigen (CEA), and carbohydrate antigen (CA15–3) was developed using single-particle, ICP-MS-based, magnetic immunoassay. Gold nanoparticles (AuNPs), ZnSe quantum dots (QDs), and Silver nanoparticles (AgNPs) were employed to tag antibodies. A highly efficient capture of CYFRA21-1, CEA, and CA15–3 was achieved using biotinylated, antibody-coated magnetic beads. AuNPs/ZnSe QDs/AgNPs-tagged second antibodies helped realize sensitive quantification of the target antigen using single particle ICP-MS. Under optimum conditions, CYFRA21-1, CEA, and CA15–3 linear concentration ranges were 0.05–50 ng mL−1, 0.02–100 ng mL−1, and 0.6–250 mU mL−1. The correlation coefficients were 0.9999, 0.9987, and 0.9970, respectively. CYFRA21-1, CEA, and CA15–3 detection limits were 0.02 ng mL−1, 0.006 ng mL−1, and 0.25 mU mL−1, respectively. Relative standard deviations (RSD) for CYFRA21-1, CEA, and CA15–3 were 3.2%, 4.4%, and 4.2%, respectively. The method simultaneously detected CYFRA21-1, CEA, and CA15–3 in human lung cancer serum samples with recoveries of between 89.8% and 101%.

Improved carrier transport in Mn:ZnSe quantum dots sensitized La-doped nano-TiO2 thin film**Project supported by the Natural Science Foundation of Hebei Province, China (Grant No. E2017203029).

Mn:ZnSe/ZnS/L-Cys core-shell quantum dots (QDs) sensitized La-doped nano-TiO2 thin film (QDSTF) was prepared. X-ray photoelectron spectroscopy (XPS), nanosecond transient photovoltaic (TPV), and steady state surface photovoltaic (SPV) technologies were used for probing the photoelectron behaviors in the Mn-doped QDSTF. The results revealed that the Mn-doped QDSTF had a p-type TPV characteristic. The bottom of the conduction band of the QDs as a sensitizer was just 0.86 eV above that of the La-doped nano-TiO2 thin film, while the acceptor level of the doped Mn2+ ions was located at about 0.39 eV below and near the bottom of the conduction band of the QDs. The intensity of the SPV response of the Mn-doped QDSTF at a specific wavelength was ∼2.1 times higher than that of the undoped QDSTF. The region of the SPV response of the Mn-doped QDSTF was extended by 191 nm to almost the whole visible region as compared with the undoped QDSTF one. And the region of the TPV response of the Mn-doped QDSTF was also obviously wider than that of the undoped QDSTF. These PV characteristics of the Mn-doped QDSTF may be due to the prolonged lifetime and extended diffusion length of photogenerated free charge carriers injected into the sensitized La-doped nano-TiO2 thin film.

A sensitive electrochemiluminescence biosensor based on metal-organic framework and imprinted polymer for squamous cell carcinoma antigen detection

An electropolymerized dopamine molecularly imprinted polymer (MIP) electrochemiluminescence (ECL) biosensor was constructed to detect squamous cell carcinoma antigen (SCCA). Besides having a large surface area, which allows the loading of more ZnSe quantum dots (ZnSeQDs), Fe(III)-MIL-88B-NH2 metal organic framework (MOF) is an efficient co-reaction accelerator that facilitates the transition of S2O82− into SO4−. As a result, the signal probe of Fe(III)-MIL-88B-NH2@ZnSeQDs/Ab has a strong ECL emission, which allowed the development of a three-way signal amplification strategy for ZnSeQDs emission. The electropolymerized dopamine MIP was found to improve the selectivity in the detection of SCCA. Under optimized conditions, the biosensor displayed a wide linear range from 0.0001 to 100 ng mL-1 with a detection limit of 31 fg mL-1. The prepared biosensor showed several advantages, including good specificity, outstanding selectivity and excellent stability. The proposed method can be used for the rapid and sensitive detection of SCCA in human serum and has promise for clinical application.

A Mn:ZnSe quantum dot-based turn-on fluorescent sensor for the highly selective and sensitive detection of Cd2+

A highly selective and sensitive nanoprobe with fluorescence turn-on sensing properties for recognizing Cd2+ was developed through replacing Mn2+ near the surface of Mn:ZnSe quantum dots.

Construction of microsphere-shaped ZnSe-AgZnInS and its charge transport property

The composite structure of ZnSe-AgZnInS microspheres was synthesized by two-step hydrothermal reaction, in which AgZnInS quantum dots (QDs) attached to the surface of ZnSe microspheres. Compared with pure ZnSe and AgZnInS QDs, the ZnSe-AgZnInS exhibited excellent photocatalytic activity for H2 generation under the illumination of a simulated sunlight. The results also showed that different mass ratios of AgZnInS QDs had a great influence on the photocatalytic performance of ZnSe-AgZnInS microspheres. When the AgZnInS QDs was 0.05 g/mol with the photocatalytic reduction time of 5 h, the H2 formation rate of ZnSe-AgZnInS reached the optimal value (343.108 μmolg−1 h−1), which was ∼20 times and more than 2 times higher than bare ZnSe and AgZnInS QDs, respectively. The related mechanism of photocatalytic hydrogen generation was investigated by suface photovoltage spectroscopy and transisent fluorescence. It was found that the efficient transport of photogenerated carriers at the interface between ZnSe and AgZnInS QDs contributed to the improvement of the photocatalytic performance of ZnSe-AgZnInS. This work provides further insights for the design and preparation of composite photocatalysts.

Efficient and sub-nanosecond resonance energy transfer in close-packed films of ZnSe quantum dots by steady-state and time-resolved spectroscopy

Abstract Quantum dots (QDs) structures have the large potential to provide new optico-electrical properties through energy transfer from small-sized QDs to large one. We study the energy transfer process and an influence of ligand on interior states QDs in ZnSe QDs films stabilized by thioglycerol. By combining a steady-state and time resolved photoluminescence spectroscopy measurements we demonstrated the high energy transfer efficiency and its effect on optical properties of random loose-packed QDs arrays. First shown that in ZnSe QDs films the energy transfer time constant can be as fast as 750 ps that is governed by the minimal inter-QDs distance (small length of the thioglycerol molecules) and strong excitons quantum confinement. We discussed also possible causes of an occurrence the so-called blocking QDs in arrays limiting the exciton transport length and energy transfer processes.

ZnSe quantum dot based ion imprinting technology for fluorescence detecting cadmium and lead ions on a three-dimensional rotary paper-based microfluidic chip

In this study, a newly fluorescent ZnSe quantum dots (QDs) with ion imprinting technology was firstly realized on the three-dimensional (3D) rotary paper–based microfluidic chip platform which can be used to realize specific and multiplexed detection of Cadmium ions (Cd2+) and Lead ions (Pb2+). Compared to CdTe quantum dots, ZnSe quantum dots are less toxic and more environmental friendly. In addition, this design improved the portability of the device by transferred the liquid phase of ZnSe QDs@ion imprinted polymers to solid glass fiber paper. Moreover, the 3D rotary microfluidic chip (μPADs) showed great advantages including low cost, simple and fast facile operation, multiplexed detection, and showed good sensitivity and selectivity. Under optimal experiment conditions, our proposed method was enabled to realize specific and multi-channel determination of Cd2+ and Pb2+ ions. The developed sensor of Cd2+μPADs provided a linear response from 1 to 70 μg/L with a lower detection limit of 0.245 μg/L, and Pb2+μPADs provided a linear response from 1 to 60 μg/L with a lower detection limit of 0.335 μg/L, respectively. Excitingly, this newly designed 3D rotary μPADs exhibited quantitative information conveniently, which showed the promising application prospects to rapid testing target metal ions in environmental in the future.

Synthesis of Alloyed ZnSeTe Quantum Dots as Bright, Color-Pure Blue Emitters.

Considering a strict global environmental regulation, fluorescent quantum dots (QDs) as key visible emitters in the next-generation display field should be compositionally non-Cd. When compared to green and red emitters obtainable from size-controlled InP QDs, development of non-Cd blue QDs remains stagnant. Herein, we explore the synthesis of non-Cd, ZnSe-based QDs with binary and ternary compositions toward blue photoluminescence (PL). First, the size increment of binary ZnSe QDs is attempted by a multiply repeated growth until blue PL is attained. Although this approach offers a relevant blue color, excessively large-sized ZnSe QDs inevitably entail a low PL quantum yield. As an alternative strategy to the above size enlargement, the alloying of high-band gap ZnSe with lower-band gap ZnTe in QD synthesis is carried out. These alloyed ternary ZnSeTe QDs after ZnS shelling exhibit a systematically tunable PL of 422-500 nm as a function of Te/Se ratio. Analogous to the state-of-the-art heterostructure of InP QDs with a double-shelling scheme, an inner shell of ZnSe is newly inserted with different thicknesses prior to an outer shell of ZnS, where the effects of the thickness of ZnSe inner shell on PL properties are examined. Double-shelled ZnSeTe/ZnSe/ZnS QDs with an optimal thickness of the ZnSe inner shell are then employed for all-solution-processed fabrication of a blue QD light-emitting diode (QLED). The present blue QLED as the first ZnSeTe QD-based device yields a peak luminance of 1195 cd/m2, a current efficiency of 2.4 cd/A, and an external quantum efficiency of 4.2%, corresponding to the record values reported from non-Cd blue devices.