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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Inserting a Low-Refractive-Index Dielectric Rear Reflector into PERC Cells: Challenges and Opportunities
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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Influence of Sn2+ ion on structural, morphological and optical characteristics of Cd0.9a??xZn0.1SnxS (0a??a?¤a??xa??a?¤a??0.06) quantum dots
摘要： Water-soluble Cd0.9-xZn0.1SnxS (0 B x B 0.06) quantum dots were prepared by dual doping of Sn and Zn via chemical co-precipitation technique. XRD results con?rmed the cubic structure of CdS crystallites without generating any secondary peaks due to doping. TEM analysis revealed the structural information of the Sn-doped CdS host. The Sn substitution enhanced the particle size lightly. The surface morphological study revealed that the agglomeration of the samples was decreased. From UV–visible optical study, it was observed that the optical transmittance was suppressed owing to Sn substitution. Absorption peaks were blueshifted, and band gap values were widened due to incorporation of Sn. The strong PL emission peaks were received at 400 nm-1 and weak peaks near 490 nm-1. The peaks originated near the UV region were due to sulfur vacancies on the surface. EDX and FTIR studies con?rmed the presence of Sn in the prepared samples. Since the possibility of tailoring the band gap toward a high energy gap, these materials composition may be selected for optoelectronic device fabrication.
关键词： Blueshift,CdS QDs,Sn,Photoluminescence,Zn
更新于2025-09-23 15:21:01
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Synthesis of Silica-Coated Csa??PbBra?? and Csa??Pb(Br0.4I0.6)a?? Quantum Dots With Long Lifetime and Enhancement in Quantum Efficiency for WLEDs Applications: Lightings With High CRI and Displays With Wide Color Gamut
摘要： To focus on developing white light-emitting diodes (WLEDs) for lightings with high color rendering index (CRI), low correlated color temperature (CCT), and the displays with wide color gamut, inorganic perovskite quantum dots (QDs) such as CsPbX3 (X = Cl, Br, I) were the promising candidate owing to the excellent optoelectronic properties such as high quantum efficiency, narrow emission wavelengths, and tunable emission spectrum. Nevertheless, the CsPbBr3QDs in the form of powders or films had a poor air stability and severe decline of quantum efficiency. Therefore, in this article, a new idea was proposed that 0-D green–red perovskite QDs powders such as Cs4PbBr6 and Cs4Pb(Br0.4I0.6)6 with improved quantum efficiency and long lifetime were first developed by silica-coated method and crystal phase transition in low-temperature synthesis. The quantum efficiency in green Cs4PbBr6 powders could be significantly enhanced from 31.41% to 45.87% and red Cs4Pb(Br0.4I0.6)6 powders was 22.79%. Moreover, the as-prepared perovskite QD powders and commercial YAG phosphors combined with blue chips were applied to high-quality WLEDs for lightings and displays. More importantly, the as-fabricated wide Commission Internationale de l’Eclairage (CIE) color gamut WLEDs for displays possessed 115% National Television System Committee (NTSC) coverage rate and luminous efficiency of 51 lm/W under 20-mA driving current. On the other hand, the constructed WLEDs for high-power lightings would generate a warm white light with a luminous efficiency of 38 lm/W, extremely high CRI of 92.8, and low CCT of 3828 K under 350 mA. Hence, the proposed green–red perovskite QD powders had outstanding potential applications in WLEDs.
关键词： white light-emitting diodes (WLEDs),0-D perovskite quantum dots (QDs),backlights of displays,solid-state lightings
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of Unauthorization at the Express-Control of Heating of Natural Gas
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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<p>Gene Expression Profiling of the Liver and Lung in Mice After Exposure to ZnO Quantum Dots</p>
摘要： Introduction: ZnO quantum dots (QDs) have drawn much attention recently as they are Cd-free, low-cost, and have excellent optical properties. With the expanded production and application of ZnO nanoparticles, concerns about their potential toxicity have also been raised. Materials and Methods: We used RNA sequencing (RNA-seq) to analyze the global gene expression of liver and lung tissues after ZnO QDs treatment. Differentially expressed genes (DEGs) were screened, with a fold change >1.5 and padj <0.05. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed, and padj <0.05 was considered significantly enriched. The RNA-seq results were validated by quantitative real-time polymerase chain reaction (qRT-PCR). Results: A total of 47 and 218 genes were significantly differentially expressed in the liver and lung. Eight GO terms were enriched in the liver and lung, and retinol metabolism and the peroxisome proliferator-activated receptor (PPAR) signaling pathway were shared in different tissues. Discussion: According to DEGs and pathway enrichment analyses, inflammation might be induced in liver and lung tissues after intravenous injection of ZnO QDs. These findings will be helpful for future research and application of ZnO QDs.
关键词： ZnO QDs,transcriptome,differentially expressed genes
更新于2025-09-23 15:21:01
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New insights into the release mechanism of Cd2+ from CdTe quantum dots within single cells in situ
摘要： Cadmium-quantum dots (Cd-QDs) possess unique properties as optoelectronic devices for sensitive detection in food and biomedicine fields. However, the toxic effects of Cd-QDs to single cells is still controversial, due to the release mechanism of QDs to Cd2+ in situ and the cytotoxic effects of QDs and Cd2+ respectively are still unclear. In this paper, the release rule of Cd2+ from CdTe QDs within single cells was investigated in situ by using flow cytometry method and the dose-response relationships were explored. Besides, an all-inclusive microscopy system was optimized for live cell imaging to observe the real-time entry process of CdTe QDs into cells. We found that intracellular CdTe QDs and Cd2+ contents were increased based on the dosage and exposing time. A dissociated saturation of Cd2+ from CdTe QDs was exist within cells. CdTe QDs induced more serious cyto-toxicity on kidney cells than hepatocytes. The toxicity of oxidative stress, cell apoptosis effects induced by CdTe QDs and Cd2+ are also in consistent with this result. This research develops analytical method to quantify the uptake and release of Cd-QDs to primary cells in situ and can provide technical support in studying the cyto-toxicity portion contributed by nanoparticles (NPs) and metal ions.
关键词： Release mechanism,Aqueous phase QDs,Single cells,Cd,In situ
更新于2025-09-23 15:21:01
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Portable Instrument for Monitoring Environmental Toxins Using Immobilized Quantum Dots as the Sensing Material
摘要： A portable instrumental system was designed for the routine environmental monitoring of toxic volatile organic compounds (VOCs) in atmospheric conditions based on changes in the photoluminescence emission of semiconductor nanoparticles (quantum dots) entrapped in a sol-gel matrix as the solid sensing material. The sol-gel sensing material displayed a long-lived phosphorescent emission, which is quenched in the presence of trace levels of a volatile organic compound (acetone) in gaseous atmospheres. The developed instrument could measure and process the changes in the photoluminescence of the sensing material after exposure to gaseous acetone. The developed prototype device consists of a deep-ultraviolet light-emitting diode (UV LED), which excites the chemical sensing material; an optical filter to remove scattered light and other non-desirable wavelengths; a photomultiplier tube (PMT) to convert the phosphorescence emission of the sensor phase to an electrical signal; and a microcontroller to correlate the signal with the analyte concentration. The developed prototype was evaluated for its ability to measure low levels of gaseous acetone in contaminated atmospheres with high sensitivity (detection limit: 9 ppm). The obtained results show the feasibility of this type of instrument for environmental analytical control purposes.
关键词： quantum dots (QDs),photomultiplier,UV LED,instrumentation,nanoparticles,room temperature phosphorescence (RTP)
更新于2025-09-23 15:21:01
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Electrogenerated Chemiluminescence and Spectroelectrochemistry Characteristics of Blue Photoluminescence Perovskite Quantum Dots
摘要： Lead-based perovskite MAPbX3 (MA= CH3NH3, X=Cl and Br) has shown great potential benefits to advance modern optoelectronics and clean energy harvesting devices. Poor structural stability is one of the major challenges of MAPbX3 perovskite materials to overcome to achieve desired device performance. Here we present the electrochemical stability study of CH3NH3PbCl1.08Br1.92 quantum dots (QDs) by electrogenerated chemiluminescence (ECL) and photoluminescence (PL) spectroelectrochemistry methods. Electrochemical anodization of pristine MAPbX3 QD film results in the disproportionate loss of methylammonium and halide ions (X=Cl and Br). ECL efficiency and stability of perovskite QDs in the presence of co-reactant tripropyl amine (TPrA) can be greatly improved after being incorporated into a polystyrene (PS) matrix. Mass spectrum and X-ray photoelectron spectroscopy (XPS) measurements are used to provide chemical composition variation details of QDs, responsible for the ECL and PL characteristics (e.g., wavelength redshift) of perovskite QDs in an electrochemical cell.
关键词： quantum dots (QDs),Perovskite,Blue light emission,nanocrystals,polystyrene (PS),electrogenerated chemiluminescence (ECL),photoluminescence (PL)
更新于2025-09-23 15:21:01
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Determination of BCM-7 based on an ultrasensitive aptasensor fabricated of gold nanoparticles and ZnS quantum dots
摘要： In this study, an ultrasensitive electrochemical aptasensor for the determination of the β-casomorphin 7 (BCM-7) as a promising biomarker of autism disorder is introduced. According to the proposed strategy, a glassy carbon electrode (GCE) was modi?ed by thiourea capped-ZnS QDs (ZnS-QDs) and gold nanoparticles (AuNPs) to further immobilization the amino-aptamer (NH2-Apt) on its surface. The NH2-Apt as a receptor of the BCM-7 was attached to the embedded surface via a formation of the Au–N bonds between the AuNPs and amino groups of the Apt. The evaluation of aptasensor by various electrochemical techniques exhibited successful sensing of the BCM-7 under two broad linear concentration ranges from 1 fM to 0.6 μM with a limit of detection (LOD) down to 350 aM. Also, the performance of the aptasensor in BCM-7 detection in real human urine samples was satisfactorily investigated. These ?ndings may facilitate distinguish of this challenging disorder and help human health.
关键词： Thiourea capped-ZnS QDs,β-casomorphin 7,Glassy carbon electrode,Gold nanoparticles,Aptasensor,Autism
更新于2025-09-23 15:21:01
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Enhanced UV-visible detection of InGaZnO phototransistors via CsPbBr3 quantum dots
摘要： Indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) exhibit high field-effect carrier mobility and low off-state current, which are attractive for high speed and low noise photodetectors and image sensor applications. However, with an optical band gap of ~3.3 eV, the photodetection range of IGZO TFTs is limited to short wavelength ultraviolet (UV) light. Here, we demonstrate a simple approach to enhance the performance of IGZO-based phototransistors by incorporating layers of solution-processed perovskite quantum dots (QDs) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Owing to the fast transfer of photogenerated electrons by CsPbBr3 QDs absorbing layer, the photoresponse of QD-decorated IGZO phototransistor is extended to the visible range (500 nm), and the responsivity and detectivity of QD-decorated device are more than two order higher than those of original IGZO TFTs. Moreover, the QD-decorated IGZO phototransistor also exhibits enhanced performance under UV light (350 nm), achieving a responsivity of 9.72 A/W, a detectivity of 2.96 × 1012 Jones, and a light to dark current ratio in the order of 106 at a wavelength of 350 nm (a light intensity of 207.3 μW/cm2).
关键词： heterojunction,CsPbBr3 QDs,IGZO,phototransistors
更新于2025-09-23 15:19:57