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The low bandgap 3-hexylthiophene/pyridine copolymers (P3HT/PY) were synthesized and the composites of P3HT/PY and CdSe QDs were prepared. The characterization are performed with 1H NMR, UV-vis, PL, TEM, XPS and cyclic voltammetry (CV). The results show that the P3HT/PY copolymers have an electrochemical bandgap of 1.67 eV, while the composites show a broader absorption and a lower bandgap than the copolymers. The highly efficient fluorescence quenching of the composites indicates that the ultrafast charge transfer happened between the P3HT/PY copolymers and the CdSe QDs. The composites show a uniform dispersion and good compatibility, and the surface chemistry study verified the chemical bonding between them. In addition, both the copolymers and the composites exhibited p- and n-type doping ability, and the P3HT/PY/CdSe composites have a better donor-acceptor match, which is a promising p-n type semiconductor material.

Highly luminescent and quantum-yielding (QY) CdSe/ZnS core/shell quantum dots (CS QDs) were synthesised via a new succession route in a non-toxic solvent, N,N-Dimethyl-octadecyl-tertiary-amine(18DMA) at a mild temperature. The CS QDs were also proven to be as efficient in reaching high quantum yields (up to 74%) as their reported high-temperature synthesis with organic phosphine ligands. It was demonstrated that the synthesis temperatures directly determine the size by controlling the rate of the monomer diffusion and adsorption. It was also found that the amount of surfactant oleic acid determined the QY of the QDs, whereas it had little influence on the crystallisation.

A low-cost, green, and reproducibly non-injection one-pot synthesis of high-quality CdS quantum dots (QDs) is reported. The synthesis was performed in the open air by mixing precursors cadmium stearate and S powder into a new solvent N-oleoylmorpholine. An overlapped nucleation-growth stage followed by a dominated growth stage was observed. The resulting QDs exhibited well-resolved absorption fine substructure and a dominant band-edge emission with a narrow size distribution (the full width at half maximum (fwhm) was only 22-24nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 46.5%. Highly monodispersed CdS QDs with tunable sizes and similar PL fwhm and QYs could also be obtained from the CdS QDs in a large-scale synthesis. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs with high crystallinity had a cubic structure. A significant PL improvement and a continuous QY increase for the CdS QDs were observed during a long storage time in air and in a glovebox under room temperature. A slow surface reconstruction was proposed to be the cause for the PL enhancement of CdS QDs., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Semiconductor quantum dots (QDs) are nanocrystals whose excitons are bound in 3D space. Owning to their remarkable quantum confinement effect, QDs exhibit a discontinuous electronic energy level structure similar to that of atoms, leading to novel physical, optical, and electrical properties for various optoelectronic device applications including solar cells. Near‐infrared photoactive narrow bandgap (NBG) QDs can maximize the use of solar energy through the quantum size effect, offering a good opportunity for designing highly efficient wide‐spectrum responsive solar cells. This review analyzes the recent research progress of NBG QDs as light absorbing materials in solar cells. The critical elaboration of the latest achievements both in material design and device optimization for NBG QD‐based solar cells (QDSCs), including QD synthesis and film fabrication, design of device configuration, classification of NBG QDs and their photovoltaic performance, strategies for performance improvements is focused upon. The current challenges and perspectives for the further advance of NBG QDSCs are also discussed. [ABSTRACT FROM AUTHOR]

Highly efficient and blue-emitting CsPbBr3 quantum dots were successfully synthesized by two-step supersaturated recrystallization under ambient condition. This method could control the particle size within 2.8 nm, thus resulting in strong quantum confinement effect of the products. The as-synthesized CsPbBr3 quantum dots presented outstanding optical properties with highest photo-luminescence quantum yield of 87.20% and longest PL lifetime of 12.24 ns. The blue light-emitting diode made from the CsPbBr3 quantum dots exhibited a CIE coordinate (0.14, 0.10), in good agreement with the standard blue CIE coordinate (0.14, 0.08) of National Television System Committee (NTSC). [ABSTRACT FROM AUTHOR]

Primary alkylamines are generally used as ligands for the synthesis of colloidal II–VI group quantum dots (QDs). However, knowledge of the effects of these ligands on the nanocrystalline structure in the literature is scarce and often contradictory. Herein, the structural evolution of CdSe QDs synthesized with primary alkylamines of different chain lengths and concentrations and at various reaction temperatures has been investigated. Absorption spectroscopy, XRD, HRTEM and Fourier transform imaging were applied to characterize the structure of the CdSe QDs. The results demonstrate that CdSe QDs preferentially form the wurtzite structure with shorter-chain and higher-concentration primary alkylamines at higher reaction temperatures. In contrast, the zinc blende structure is formed in the presence of longer-chain and lower-concentration primary alkylamines at lower reaction temperatures. By precisely controlling the experimental conditions, CdSe QDs with a pure zinc blende phase have been successfully achieved. [ABSTRACT FROM AUTHOR]

Environment-friendly CuInZnS (CIZS) core and CuInZnS/ZnS (CIZS/ZnS) core/shell quantum dots (QDs) were synthesized via a facile solution-phase method. Different methods certified that the ZnS shell was successfully coated on CIZS core. The coating of ZnS shell would lead to the quantum yield increase and optical spectra blue shifted. Furthermore, the CIZS and CIZS/ZnS had a long PL lifetime of 257.3ns and 411.6ns, respectively. Finally, the CIZS/ZnS QDs powder with yellow emission was used to compose white light emitting diodes (WLED) on blue LED chip. The WLED had a of 80, of 4793K, and CIE coordinates of (0.346, 0.321) under 20mA current, and had a bright warm white emission, which indicated the promising potential of the CIZS/ZnS QDs in the optoelectronics. The synthesis of CIZS/ZnS QDs through a simple one-pot facile solution-phase strategies was shown. The resulted CIZS/ZnS QDs have a high crystallinity, tetragonal chalcopyrite structure, bright yellow emission and longer PL lifetime. Additionally, high color quality white QD-LED was also fabricated. [ABSTRACT FROM AUTHOR]

Cesium lead halide quantum dots (QDs) have tunable photoluminescence that is capable of covering the entire visible spectrum and have high quantum yields, which make them a new fluorescent materials for various applications. Here, the synthesis of CsPbX3 (X = Cl, Br, I, or mixed Cl/Br and Br/I) QDs by direct ion reactions in ether solvents is reported, and for the first time the synergetic effects of solvent polarity and reaction temperature on the nucleation and growth of QDs are demonstrated. The use of solvent with a low polarity enables controlled growth of QDs, which facilitates the synthesis of high-quality CsPbX3 QDs with broadly tunable luminescence, narrow emission width, and high quantum yield. A QD white LED (WLED) is demonstrated by coating the highly fluorescent green-emissive CsPbBr3 QDs together with red phosphors on a blue InGaN chip, which presents excellent warm white light emission with a high rendering index of 93.2 and color temperature of 5447 K, suggesting the potential applications of highly fluorescent cesium lead halide perovskite QDs as an alternative color converter in the fabrication of WLEDs. [ABSTRACT FROM AUTHOR]

Bead-based suspension arrays have attracted increasing attention because of the fast growing requirements for high-throughput multiplexed bioassays. Here, novel dual-encoded microbeads (DEBs) based on a host-guest structure are developed. A strawberry-like structure composed of thousands of dye-doped nanoparticles closely packed onto the quantum dot-encoded microbeads is designed and synthesized. Using this 3D structure, the encoded space is fully developed for multicolor encoding. As a result, a 30-barcode library with an outstanding encoding capacity is successfully established and easily decoded via flow cytometry. The separation of organic dyes and quantum dots into two building blocks helps circumvent the optical mutual interference commonly observed in most multicolor barcodes, bringing great convenience for next-step decoding accuracy. As a proof of concept, six typical DEBs are chosen and their feasibility in six-plexed detection for influenza viruses is evaluated. The results show that DEBs can selectively capture the specific targets, with negligible nonspecific absorption; these results thus demonstrate the strong potential of the DEBs as a robust platform for multiplexed bioassays. [ABSTRACT FROM AUTHOR]

A surface atomic-ligand exchange method is applied the first time in the construction of photodetectors (PDs) based on PbS quantum dots (QDs) for ultrasensitivity. The device thus produces a high photosensitivity to visible and near-infrared light with a photoresponsivity up to 7.5 × 103 A W−1 and a high stability in air. In particular, these PbS-QD-based PDs show the capability of following a pulse light with a frequency up to 100 kHz well at a relatively fast response time/recovery time of ≈4/40 μs, much faster than most previous QD-based PDs. The short response time is attributed to modification for the surface of the PbS-QDs by cetyltrimethylammonium bromide treatment, which effectively improves the contact between the QDs and the Au electrodes, leading to extracting a high carrier mobility (≈0.142 cm2 V−1 s−1). These findings show the great potential of PbS-QDs as high-speed nano-photodetectors, and, more importantly, demonstrate the importance of the surface atomic-ligand exchange method in the construction of QD-based devices. [ABSTRACT FROM AUTHOR]

Size-dependent Stokes shift of PbS quantum dots (QDs) formed in the glasses was investigated. PbS QDs with diameters of 3.5 nm to 13.3 nm were precipitated in silicate glasses with different S/Pb ratios using the conventional thermal treatment method. Absorption and photoluminescence (PL) of PbS QDs were tuned from ~0.9 µm (1.38 eV) to ~2.3 µm (0.54 eV) by adjusting the diameters of PbS QDs from 3.5 nm to 13.3 nm. PL energies of QDs exhibited linear dependence on the absorption energies with a slope of 0.484 for PbS QDs with band gap energies larger than 0.98 eV, and the maximum Stokes shift was found to be 206.2 meV for 3.5 nm-sized PbS QDs. For large PbS QDs with band gap energies smaller than 0.98 eV, Stokes shift was found to be ~20 meV or smaller. The size-dependent Stokes shift indicated that surface defects made the main contribution and relative energy positions of these surface defects were strongly dependent on the size of PbS QDs. [ABSTRACT FROM AUTHOR]

Abstract: Binary CdS and ZnS and ternary CdZnS alloy quantum dots (QDs) were synthesized via a simple, inexpensive, and reproducible route using sulfur, cadmium stearate, and zinc stearate as precursors and N-oleoylmorpholine as the reaction medium and solvent. Both binary and ternary QDs exhibited a narrow size distribution and high crystallinity as confirmed TEM and HRTEM images. The alloy QDs exhibited excellent composition-dependent optical properties and a narrow full-width at half maximum of 19–21 nm. UV-visible absorbance and photoluminescence (PL) emission spectra of the CdZnS QDs showed a blue shift during growth, indicating the formation of alloy QDs. ZnS shells were successively coated onto the alloy core via decomposition of zinc diethyldithiocarbamate at a relatively low temperature. The CdZnS/ZnS core/shell QDs obtained showed a significant increase in size and exhibited strong band edge emission with a significant increase in PL quantum yield. XRD patterns revealed that all the QDs had a zinc blende structure. The QD diffraction peaks gradually shifted to higher angle in the order CdS < CdZnS < CdZnS/ZnS < ZnS. The mechanism for the synthesis of CdZnS alloy and CdZnS/ZnS core/shell QDs is discussed. [Copyright &y& Elsevier]

A bulk-heterojunction hybrid solar cell based on CdS quantum dots (QDs) as electron acceptor and P3HT as donor was fabricated for the first time. The CdS QDs synthesized by a one-pot method had good crystallinity and stability. The hybrid thin film of CdS-QDs and conjugated polymer was made by simple spin-coating deposition of CdS-QDs/P3HT composite solution on ITO substrates and then treated by bidentate ligand ethanedithiol. Under AM1.5G illumination, the power-conversion efficiency (PCE) of the thiol-treated monolayer film was more than three times higher than that of the untreated device. The hybrid solar cell based on the assembled trilayer blend film with ethanedithiol by a layer-by-layer approach exhibited a further improved PCE of 0.86%, which was sixfold higher than that of the thiol-treated monolayer device. The results can be explained via ethanedithiol effectively displacing the existing stearate ligands on the surface of QDs in situ and connecting nanoparticles by its end function group, shortening the interdot space and thus improving electron transport between the QDs. The morphology of the thiol-treated blend film was briefly investigated. [ABSTRACT FROM AUTHOR]

A facile green approach has been developed to control the growth regime in the aqueous synthesis of CdxZn1-xTe semiconductor quantum dots (QDs) based on the electrochemistry method. The Low growth temperature and slow injection of Te precursor are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during the nanocrystal growth. The experimental results showed that a low concentration of Te precursor will definitely influence the growth procedure. The UV-visible absorption spectra, as well as transmission electron microscopy (TEM) shows the QDs a good monodispersity at any interval of the reaction procedure. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The size and composition-dependent fluorescent emission wavelength of the resultant CdxZn1-xTe alloyed QDs can be tuned from 460 to 610 nm, and their photoluminescent quantum yield can reach up to 70%. Especially in the wavelength range of 510-578 nm, the overall PL QYs of the as-prepared CdxZn1-xTe QDs were above 50%. The current work suggests that electrochemical method is an attractive approach to the synthesis of high-quality II-VI ternary alloyed semiconductor QDs at large-scale with a prominent cost advantage. [ABSTRACT FROM AUTHOR]

Abstract: Highly luminescent blue-emitting CdS/ZnS core/shell quantum dots (QDs) were synthesized in N-oleoylmorpholine by two facile steps: first, the CdS core QDs were prepared via a simple one-pot method involving a direct reaction of Cd precursor cadmium stearate and S precursor S powder in solvent N-oleoylmorpholine; second, ZnS shells were successively overcoated on CdS core through the decomposition of single molecular precursor zinc diethyldithiocarbamate. The thickness of shell was precisely tuned by controlling drip feed speed and amount of shell precursor. The obtained CdS/ZnS core/shell QDs showed the maximum photoluminescent quantum yield of 54.8% and narrow spectra bandwidth, exhibiting high monodispersity, good color purity and long fluorescent lifetimes. The CdS/ZnS core/shell QDs with tunable emission wavelength of 424–470nm were obtained by controlling the thickness of ZnS shell overgrown on different-sized CdS QDs, which are promising materials for blue light-emitting devices. [Copyright &y& Elsevier]

Abstract: The stearate-capped CdTe quantum dots (QDs) have been first prepared via direct reaction of cadmium stearate with Te powder in N-oleoylmorpholine solvent, which was a kind of clean, air-stable and conveniently synthesized acylamide, and can readily dissolve precursors cadmium stearate and Te powder at a relative low temperature. The as-prepared CdTe QDs exhibited size-dependent optical properties, steep absorbance edge and narrow photoluminescence full width at half maximum. The high-resolution transmission electron microscopy images and X-ray diffraction revealed that the highly monodisperse CdTe QDs were of regular spherical morphology with zinc blende crystal structure displaying mean sizes of about 4nm. The energy dispersed spectrometry measurement indicated the presence of Cd and Te, with the Cd:Te ratio being close to 1:1. Fourier transform infrared transmission spectra confirmed the existence of stearate on the CdTe QDs surfaces. The experimental results also demonstrated that the stearate-capped CdTe QDs had an unexpected good stability. [ABSTRACT FROM AUTHOR]

ZnSe quantum dots (QDs) and flower-shaped nanocrystals (NCs) were successfully synthesised via a cheap, green and nontoxic route, using environmentally friendly N, N-dimethyl-oleoyl amide as the solvent of Se. The experimental results show that the as-prepared ZnSe QDs with a zinc-blende structure have a narrow size distribution and without resorting to any as-synthetic size-selective procedure. A systematic study of the ZnSe QDs formation process indicates the following properties: variation of some reaction parameters allows us to tune the particle sizes and plays a greater role in the determination of the monodisperse characterisation, for example, these parameters include the amount of ligand and precursors, the injection temperature of Se solution. These size tunabilities interpreted well by the growth kinetics. Another interesting result is that the ZnSe QDs aggregate to flower-shaped NCs, and the flower-shaped NCs also have size-dependence quantum effects as the prepared disperse ZnSe QDs. [ABSTRACT FROM AUTHOR]

Abstract: High-quality CdSe quantum dots with less common zinc blende structure were prepared in non-coordinating solvent 1-octadecene, with environment-friendly N,N-dimethyl-oleoyl amide as an alternative chemical to replace trioctylphoshine for Se powder, oleic acid as primary capping ligands, and benzophenone as secondary ligands. The temporal evolution of the optical properties of the nanocrystals with different growth temperature was monitored. Significant redshifts occurred with the increase of the growth temperature. The sharpness of the first absorption peaks and the narrow emission band with full width at the half-maximum of about 30nm indicates that the size distribution of the resulting quantum dots is narrow. [Copyright &y& Elsevier]

Abstract: A much cheaper and greener route to monodisperse CdSe quantum dots (QDs) with zinc-blende structure has been developed. The N,N-dimethyl-oleoyl amide was chosen as the solvent, eliminating the needs of air-sensitive and toxic trioctylphosphine (TOP) or tributylphosphine (TBP), and cadmium oxide and elemental selenium as sources. The as-prepared CdSe QDs show an apparent blue-shift in the ultraviolet and visible (UV–vis) absorption peaks. The emission peak of the QDs can be tuned by changing synthesis time only. [Copyright &y& Elsevier]

Dual‐encoded microbeads with host–guest structures can be designed as barcodes for bead‐based suspension arrays, as described by H. Xu, H. Gu, and co‐workers on page 6146. Precise and flexible tuning of fluorescence intensity through controlled preparation results in a barcode library with enormous encoding capacity. Barcodes fixed with capturing succeed in recognizing specific target analytes and demonstrate to be a multiplexed bioassay platform with excellent prospects. [ABSTRACT FROM AUTHOR]

Colloidal hybrid perovskite quantum dots (QDs) of formamidinium lead halides (FAPbX 3 , X = Cl, Br, I and their mixture), which possess a full visible waveband tunable photoluminescence ranging from 429 nm to 782 nm verified by the calculated bandgap of FAPbX 3 (2.720eV–2.115eV–1.401eV; from Cl to Br to I) , have been prepared by regulating the halogen in FAPbBr 3. Herein, the as-obtained FAPbX 3 QDs feature a high quantum yield up to 85% and narrow emission line-widths low to 20 nm, benefiting from the highly uniform cubic morphology. In addition, the mechanism of anion-exchange in FAPbX 3 QDs is expounded from two aspects of defects and temperature by theoretical calculation and experiment method. Trichromatic LEDs are fabricated to demonstrate the photoelectric properties by employing the FAPbX 3 QDs, which have a pure color and narrow full width at half maximum (FWHM, 20.6 nm for Blue, 22 nm for Green, 36.6 nm for Red, respectively). More interestingly, the green one reaches the Rec.2020 standard and the corresponding QD white LED presents a high luminous efficiency of 48.8 lm/w and color rendering index (CRI) 90.2 together with the CIE color coordinate at (0.32,0.31). • The FAPbX 3 QDs tuned from 429 nm to 782 nm are synthesized by anion-exchange. • The mechanisms of exchange process and the band structure are expounded. • The obtained QDs feature a high PLQY up to 85% and narrow FWHM low to 20 nm. • WLEDs are fabricated with high luminous efficiency (48.8 lm/w) and CRI (90.2). [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Quantum dot light-emitting diode (QLED) displays are considered a next-generation technology, but previously reported quantum dots (QDs) consisting of heavy metals are toxic and harmful. This work examined earth-abundant, metal-free, graphitic C 3 N 4 (g-C 3 N 4) with exceptional optical and electronic properties, excellent chemical and thermal stability, an appropriate band gap, and non-toxicity for QLED applications. The dependence of the luminescence performance on the reaction atmosphere and temperature; the transformation of the crystal and electronic structures during the reaction, including crystal defects and surface functional groups; and the luminescence mechanisms of g-C 3 N 4 were uncovered. The highest quantum yield of 49.8% was achieved by the sample possessing the highest graphitic-to-triazine carbon ratio synthesized at 500 °C under N 2 atmosphere. The disappearance of the charge-transfer band, crystal defects (traps), and non-radiative transition (due to fast relaxation) from the absorption spectra demonstrates the enhanced quantum efficiency of the g-C 3 N 4 QDs over that of the bulk powders. A QLED prototype device employing g-C 3 N 4 QDs as the blue-emitting layer was demonstrated. [ABSTRACT FROM AUTHOR]

A facile synthesis of aqueous CdZnTe quantum dots (QDs) incorporated in CaCO 3 matrix is demonstrated, providing a new type of solid-state light conversion material. Highly luminescent CdZnTe QDs were firstly synthesized using CdCl 2 , ZnCl 2 and Te as precursors and 3-Mercaptopropionic acid (MPA) as ligand. Then CdZnTe QDs were incorporated into CaCO 3 matrix through a co-precipitation method. Due to the protection of the tight matrix, the resulting CdZnTe QDs/CaCO 3 composites exhibit good photostability and processability as well as high photoluminescence properties. A white light-emitting diode (WLED) applying the composites as a red color conversion layer was also fabricated, which showed excellent performance including a Commission Internationale de I'eclairage (CIE) color coordinate of (0.3662, 0.3396), a high color rendering index (Ra) of 92.7 and a low correlated color temperature (Tc) of 4146 K under 20 mA forward-bias current, suggesting the promising application of the composites in solid-state lighting systems. [ABSTRACT FROM AUTHOR]

Here we present the observation of a unique phenomenon of converting electrical conductivity types in surface atomic-ligand exchanged of PbS quantum dots (QDs), while tuning the gate voltage of PbS QD-based thin film field-effect transistors (TFTs). The synthesized PbS-QD thin films showed different conductivity (n- or p-) types depending on the direction of gate voltage sweeping. When increasing gate voltage from negative to positive voltage, the TFT devices produced n-channel characteristics with a typical mobility on the order of μ n = 10 −1 cm 2 V −1 s −1 . By contrast, the devices showed p-channel characteristics with similar mobility when sweeping the gate voltage from positive to negative. The studies based on density functional theory (DFT) theoretical calculations and X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the band gap of ligand exchanged PbS-QDs changes upon gate voltage sweeping, affecting the surface states of the QDs due to the adhered Br − and therefore altering the conductivity type of the materials. These findings signify the carrier type switching behavior via gate voltage tuning in atomic-ligand exchange QD thin films, suggesting great application potential of QD for advanced new-generation nano-electronic devices. [ABSTRACT FROM AUTHOR]

Herein, we report a facile method of direct photodissociation of toluene molecules to photoluminescent carbon dots (CDs) under pulsed laser irradiation in the absence of surfactants or catalysts. The as-synthesized CDs with diameters 1.3–4.0 nm present regular emission peaks and the crystallographic structure of these species has been identified as graphite 2H from the analysis of high resolution transmission electron microscope (HRTEM) images, X-ray photoelectron spectroscopy (XPS) and Raman spectrum. In addition, First-Principle calculations were performed to discuss the photon-induced excitation in the photodissociation process. The results demonstrate that electrons can be transited from Highest Occupied Molecular Orbital (HOMO) to Lowest Unoccupied Molecular Orbital (LUMO) in toluene molecule by 248 nm single photon excitation process and the Stark effect plays a crucial role in the photodissociation process. These CDs exhibit excellent stable emission due to the stability of crystal structure, which could be considered for promising luminescent applications. [ABSTRACT FROM AUTHOR]

Colloidal quantum-dot (QD) solar cells have emerged as one of the most promising photovoltaic techniques. Herein, we report an inverted PbS QD solar cells employing solution-processed CdS as the electron acceptor materials. Chemical bath deposition – one featuring ease of fabrication and compatibility with a low-temperature process – was employed to prepare CdS film on FTO glass, followed by deposition of PbS QDs as absorbing layer in a layer-by-layer fashion, thereby forming a depleted heterojunction structure. The results suggested that the thickness of CdS layer can be a key factor for determining the photovoltaic performance. After systematical optimization, an inverted FTO/CdS/PbS QDs/MoO 3 /Ag structure with an ultra-thin CdS film of 40 nm delivered a decent power conversion efficiency of 5.22%. The maximum temperature is ~85 °C via device fabrication demonstrates potential large-scale production process. [ABSTRACT FROM AUTHOR]

Abstract: In this letter, Mn2+-doped CdS quantum dots were successfully synthesized with stearic acid as the stabilizer by a nucleation-doping method. Generally, Mn2+-doped emission was at ~585nm, which was well-established due to 6A1–4T1 transition of Mn2+ ions. Interestingly, a high-luminescence Mn2+-doped emission at ~563nm was observed in the Mn2+-doped CdS nanocrystals. This large blue shift explained that Mn2+ ions were deeply doped in nanoparticle cores in our doping method, leading to less splitting of Mn2+ energy level. The results of transmission electron microscopy and X-ray diffraction also demonstrated the small particle size (~4.2nm), monodispersity and high crystallinity. The quantum yield of the as-prepared nanocrystals was calculated ~41%. [Copyright &y& Elsevier]

Formation of PbS QDs in the glasses containing a small amount of lead oxide was examined. Oversaturation of sulfur only was sufficient to promote the formation of PbS QDs in the glasses. Upon thermal treatment, absorption of PbS QDs was tuned from 824nm to 2213nm. Infrared photoluminescence, especially, mid-infrared photoluminescence from PbS QDs was observed in the range of 1008nm to 2182nm. Ostwald ripening of PbS QDs occurred when the heat-treatment temperature was 530°C or 540°C, and led to the decrease in the absorption coefficients and splitting of the photoluminescence bands. [ABSTRACT FROM AUTHOR]

[Display omitted] • The in-situ polymerization via illuminating and methyl methacrylate was firstly proposed. • The hybrid FAPbBr 3 QDs-polymer nanocomposites show enhanced stability and fluorescence. • The transparent nanocomposite films with strong blue, green and red emission were prepared in large area. • High color temperature and lumen efficiency WLED was constructed. It has been proved that perovskite quantum dots (QDs) have great potential in optoelectronic devices because of their excellent optical performance. However, low stability against water and oxygen environment hinders the commercial application of down-conversion display films on account of its highly ionic nature and low formation energy. Here, we demonstrate a convenient method to obtain a uniform, large-area water-oxygen-resistant quantum dot-polymer composite film via illuminating FAPbBr 3 QDs and methyl methacrylate (MMA) under white light emitting diode. We find that FAPbBr 3 QDs act as photo initiators, leading to the polymerization of organic monomers around the quantum dots. The obtained FAPbBr 3 QDs-polymer nanocomposites are independently dispersed coated with about 10 nm thick polymerized methyl methacrylate (PMMA). Due to the well protection of covered PMMA, the FAPbBr 3 QDs/PMMA nanocomposites show high tolerance to water and oxygen, and the increased PLQY and lifetime indicate the reduction of non-radiative recombination centers. Furthermore, the FAPbBr 3 QDs/PMMA nanocomposites are easy to produce large area films, and no agglomeration during films production by knife coating process. Then uniform, strong fluorescence, transparent and stable blue, green and red nanocomposite films can be prepared by optimizing the viscosity via controlling the reaction time. Finally, white LED was fabricated with a Lumen Efficiency of 80.4 m/W and Color Rendering Index of 90. Our work suggests that illuminated polymerization of perovskite quantum dots under white light emitting diode provides a simple and effective method to commercialization [ABSTRACT FROM AUTHOR]