- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Influence of PbS Quantum Dots-Doped TiO2 Nanotubes in TiO2 Film as an Electron Transport Layer for Enhanced Perovskite Solar Cell Performance
摘要： Lead sulfide quantum dots-doped titanium dioxide nanotubes (PbS QDs-doped TNTs) were successfully prepared by the hydrothermal and impregnation methods. A thin layer of titanium dioxide (TiO2) comprising of PbS QDs-doped TNTs was applied as an electron transport layer (ETL) in order to improve the planar perovskite solar cell efficiency. The role of incorporating a high surface area of one-dimensional nanotube structure of TiO2 in the conventional TiO2 layer provided a special unidirectional charge transport and a high charge collection. Moreover, doping PbS QDs onto the surface of TNTs modified the electronic and optical properties of the ETL by downshifting the conduction band of TiO2 from ?4.22 to ?4.58 eV, therefore promoting the driving force of an electron injection to the transparent conductive electrode. By varying the concentration of PbS QDs-doped TNTs dispersed in 2-butanol from 0.1 to 0.9 mg/mL, a concentration of 0.3 mg/mL PbS QDs-doped TNTs was the optimum concentration to be mixed with TiO2 solution for the ETL deposition. The best perovskite solar cell performance with the optimum loading of PbS QDs-doped TNTs provided 14.95% power conversion efficiency, which was increased from 12.82% obtained from the cell with pristine TiO2 film as ETL.
关键词： PbS quantum dots (PbS QDs),perovskite solar cells (PSCs),TiO2 nanotubes (TNTs),Electron transport layer (ETL)
更新于2025-09-11 14:15:04
-
Nitrogen donor ligand for capping ZnS quantum dots: a quantum chemical and toxicological insight
摘要： Nanoparticles having strong optical and electronic properties are the most widely used materials in sensor development. Since the target analyte interacts directly with the surface of the material, the choice of ligand for functionalizing the surface of the material is the key for its further applications. The functionalized surface of the material makes it suitable for required applications as it controls the size of the particle during its growth from the solution phase. Biomolecule capped nanomaterials are favourable for various applications in bio-sensing. In the present work, an attempt has been made to explore the biologically active molecule imidazole as capping agent for ZnS semiconductor nanoparticles or quantum dots (QDs). This work explores the possibility of replacing conventional thiol-zinc bonding and hence paves new pathways for biomolecules having the possibility of being efficient capping agents. Computational chemistry has been used to study the mechanism of bonding between one of the nitrogen atoms of imidazole and the zinc ion of the ZnS QDs. The quantum chemical insight not only explores the most spontaneous interaction of zinc ion and imidazole molecule so as to act as an efficient capping agent but also explains the probable bonding site for nitrogen–zinc chemistry. The tailormade Mn doped ZnS QDs are one of the most promising materials for probe and sensor development. The ZnS core having non-toxicity and the emission in longer wavelength due to manganese makes this material highly useful biologically. The aqueous route of synthesis has been employed to obtain a highly homogeneous and pure material which was further characterized by UV (Ultra Violet spectroscopy), Spectrofluorometer, Transmission Electron Microscope and X-ray Diffraction. The toxicity at the cellular and genetic levels was also investigated to prove the potential of the imidazole capped Mn doped ZnS QD as a biocompatible material.
关键词： quantum chemical,Nitrogen donor ligand,biocompatibility,capping agent,toxicological insight,ZnS quantum dots,Mn doped ZnS QDs,aqueous synthesis,imidazole
更新于2025-09-11 14:15:04
-
Correlations between optical properties and Voronoi-cell area of quantum dots
摘要： A semiconductor quantum dot (QD) can generate highly indistinguishable single photons at a high rate. For application in quantum communication and integration in hybrid systems, control of the QD optical properties is essential. Understanding the connection between the optical properties of a QD and the growth process is therefore important. Here, we show for GaAs QDs, grown by infilling droplet-etched nanoholes, that the emission wavelength, the neutral-to-charged exciton splitting, and the diamagnetic shift are strongly correlated with the capture-zone area, an important concept from nucleation theory. We show that the capture-zone model applies to the growth of this system even in the limit of a low QD density in which atoms diffuse over μm distances. The strong correlations between the various QD parameters facilitate preselection of QDs for applications with specific requirements on the QD properties; they also suggest that a spectrally narrowed QD distribution will result if QD growth on a regular lattice can be achieved.
关键词： capture-zone model,optical properties,Voronoi-cell area,GaAs QDs,quantum dots
更新于2025-09-11 14:15:04
-
Concentration dependent thermo-optic properties of yellow emissive ZnO quantum dots
摘要： This paper study the thermal properties of ZnO quantum dots (QDs) synthesized by sol-gel method. The structural and morphological properties were investigated using x-ray diffraction technique (XRD) and transmission electron microscopy (TEM). Thermal properties of ZnO QDs were measured using dual beam mode matched thermal lens technique. The results reveal that the thermal diffusivity of the nano?uid depends on the concentration of ZnO QDs. There is an optimum concentration of ZnO QDs, above which thermal diffusivity increases more than that of the base ?uid whereas thermal diffusivity decreases below the optimum concentration. This variation in thermal diffusivity of ZnO QDs nano?uid is explained using absorption and emission spectra.
关键词： optical properties,ZnO QDs,thermal properties,nano?uids
更新于2025-09-11 14:15:04
-
Detection of theophylline using molecularly imprinted polymers based on thioglycolic acid-modified CdTe quantum dots
摘要： Molecularly imprinted polymers (MIPs) and quantum dots (QDs) have been widely employed to fabricate highly sensitive and selective sensor. Here, we developed a fluorescence nanosensor based on thioglycolic acid-modified CdTe QDs that is coated with molecularly imprinted polymers for the specific detection of theophylline (THP). Initially, water-soluble thioglycolic acid-modified CdTe QDs were synthesized by refluxing method. Then, MIPs-coated QDs (MIPs-QDs) composite was produced by sol–gel process using THP as a template. Therefore, the selectivity of the molecular imprinting technique and advantages of QDs were combined. The prepared QDs and the MIPs-QDs were characterized using X-ray diffraction technique, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and fluorescence spectrometry. Finally, this sensing system was successfully used to detect THP in human plasma samples with recoveries of 90% to 108%. A very good linear relationship was observed between the decreasing in the fluorescence intensity of MIPs-QDs and increasing the THP concentration within concentration range of 0.14–3.05 μmol L?1, with a correlation coefficient of 0.9992 and detection limit of 0.07 μmol L?1.
关键词： Molecularly imprinted polymers,Thioglycolic acid-modified CdTe QDs,Theophylline
更新于2025-09-11 14:15:04
-
ZnSe:Cu/ZnS:Cu quantum dots (QDs): synthesis via a simple UV-assisted approach and investigating optical properties
摘要： In this report, first, ZnSe:Cu QDs have been grown by a simple, rapid, and room temperature UV-assisted approach. Then by a one-pot approach, synthesized QDs were shelled by an inorganic ZnS shell. ZnS shell was grown using UV-sensitivity of Na2S2O3. Synthesized QDs were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), UV–Visible (UV–Vis), and photoluminescence (PL) analysis. ZnS shell growth resulted in increasing green emission of the ZnSe:Cu QDs and PL intensity was increased significantly by ZnS:Cu shell growth. The optimum value of the PL intensity was obtained for ZnSe:Cu(1.5%)/ZnS:Cu(0.05%).
关键词： optical properties,UV-assisted synthesis,ZnS shell,photoluminescence,ZnSe:Cu QDs
更新于2025-09-11 14:15:04
-
[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Characteristics of 1.3μm Electrically Pumped InAs/AlGaInAs Quantum Dot Lasers on (001) Silicon
摘要： We present preliminary characterization results of the first InAs/InAlGaAs/InP 1.3μm quantum dots (QDs) laser directly grown on (001) silicon. A threshold current density of 1.05 kA/cm2 under pulsed current injection has been obtained. A 50 ns width optical pulse was observed under gain-switching measurement.
关键词： InAs-InAlGaAs-InP QDs,1.3μm lasers,gain-switching
更新于2025-09-11 14:15:04
-
Copper indium sulphide:zinc sulphide (CIS:ZnS)-alloyed quantum dots as an eco-friendly absorber in solar cells
摘要： Synthesis and characterization of less toxic copper indium zinc sulphide (CIS:ZnS)-alloyed quantum dots (QDs) were carried out and the ligand exchange process towards the ef?ciency enhancement in CIS:ZnS QD-sensitized solar cell was demonstrated. The colloidal CIS:ZnS QDs were synthesized by an inexpensive heat up method with oleic acid as the capping ligand. The optical properties were analysed through ultraviolet–visible absorption and photoluminescence emission spectroscopy. The in?uence of the ligand exchange process on the CIS:ZnS QD-based solar cells was analysed with the fabrication of two batches of solar cells. The ligand exchange process was con?rmed from Fourier transform infrared and thermogravimetric analyses. The QD-sensitized solar cells were fabricated using a CIS:ZnS QD-loaded titania photoanode and by employing copper sulphide as the counter electrode. The photovoltaic performance of the fabricated QD solar cells was analysed through photovoltaic characterization methods (current density–voltage characteristics of the devices under the simulated solar light conditions and external quantum ef?ciency measurements). The ligand-exchanged QD-loaded solar cells show enhanced power conversion ef?ciency compared to the long chain ligand-capped CIS:ZnS QD-sensitized solar cells.
关键词： Copper indium zinc sulphide,less hazardous QDs,ligand exchange,oleic acid,ef?ciency enhancement,QD-sensitized solar cells
更新于2025-09-11 14:15:04
-
Photoluminescence Decay of Colloidal Quantum Dots: Reversible Trapping and the Nature of the Relevant Trap States
摘要： Interfaces are crucial factors in shaping the properties of colloidal quantum dots (QDs), in particular the size-dependent optical properties that are a hallmark of these materials. However, the role played by the interfaces associated with QDs on the kinetics of photoluminescence (PL) decay of these nanocrystals is not fully understood even for the most extensively investigated II-VI QDs. In particular, interfaces are a hotbed of trapping sites over which control is essential for efficient performance of QD-based devices, because traps condition PL lifetimes and may be related to PL intermittency. In this work, we analyze the room-temperature PL decay of drop-cast films of CdSe/ZnS QDs varying a number of factors (casting solvent, capping ligands, core/shell interface character). We show how the use of a function that accounts for reversible trapping of photogenerated charge carriers with physically meaningful parameters (time constant, trapping and detrapping rate constants, and average number of traps per QD) can provide valuable information concerning the relevant interfaces, and therefore the nature of the trap states, involved in the recombination of those charge carriers. This approach should be applicable to QDs of a variety of compositions as well as materials beyond inorganic semiconductors.
关键词： photoluminescence decay,trap states,reversible trapping,CdSe/ZnS QDs,colloidal quantum dots
更新于2025-09-11 14:15:04
-
ZnO Quantum Dots Modified by pH-Activated Charge-Reversal Polymer for Tumor Targeted Drug Delivery
摘要： In this paper, we reported a pH responsive nano drug delivery system (NDDS) based on ZnO quantum dots (QDs) for controlled release of drugs. Zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) were introduced to modify ZnO QDs, which can help enhance water stability, increase blood circulation time, and promote endocytosis. After tuning of PCBMA/PDMAEMA ratios, the ZnO@P(CBMA-co-DMAEMA) nanoplatform shows a sensitive switch from strong protein adsorption resistance (with negatively charged surface) at physiological pH to strong adhesion to tumor cell membranes (with positively charged surface) at the slightly acidic extracellular pH of tumors. Anti-cancer drug, Doxorubicin (DOX), molecules were demonstrated to be successfully loaded to ZnO@P(CBMA-co-DMAEMA) with a relatively large drug loading content (24.6%). In addition, ZnO@P(CBMA-co-DMAEMA) loaded with DOX can achieve lysosomal acid degradation and release of DOX after endocytosis by tumor cells, resulting in synergistic treatment of cancer, which is attributed to a combination of the anticancer effect of Zn2+ and DOX.
关键词： Zinc oxide quantum dots (ZnO QDs),poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA),drug delivery,poly(carboxybetaine methacrylate) (PCBMA)
更新于2025-09-10 09:29:36