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Advanced material system for the design of an intermediate band solar cell: Type-II CdTe quantum dots in a ZnCdSe matrix
摘要： We explore CdTe fractional monolayer quantum dots (QDs) in a ZnCdSe host matrix for potential application in an intermediate band solar cell device. Careful consideration has been taken during the initiation of the growth process of QDs by migration enhanced epitaxy, in order to avoid the formation of undesirable interfacial layers that can form due to the lack of common anion between the two materials. A superlattice structure of 100 periods of alternating QD and spacer layers is analyzed by high-resolution X-ray diffraction (XRD) and photoluminescent (PL) spectroscopy. Simple arguments are used following continuum elastic theory to deduce the size of the dots and the strain within the superlattice from XRD data. This is further verified using PL and used in the energy calculations that yield the values of the intermediate band energy. The results suggest that the optimized materials are highly suitable for these high efficiency solar cells.
关键词： migration enhanced epitaxy,ZnCdSe,CdTe,quantum dots,photoluminescent spectroscopy,intermediate band solar cell,high-resolution X-ray diffraction
更新于2025-09-12 10:27:22
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Simple preparation of fluorescence probe based on CdTe quantum dots combined with MIP for selective detection of sulfadimidine
摘要： A simple fluorescence sensor for the detection of sulfadimidine (SM2) was fabricated by molecular imprinting technology. Cadmium telluride quantum dots (CdTe QDs) as the fluorescent material, 3-aminopropyltriethoxysilane (APTES) as functional monomer, sulfadimidine as template molecule and tetraethoxysilane (TEOS) as cross-linker, the CdTe QDs were embedded in silica nano-particles by reverse microemulsion method. Under optimal detection condition, response is linear in the 2–30 μmol L?1 SM2 concentration condition with the detection limit was 0.4 μmol L?1. In addition, the correlation coefficient was 0.9857 and the imprinting factor was 4.82. The fluorescent probe was successfully applied to the determination of SM2 in tap water and milk sample with the spiked recoveries ranging from 99.8 to 103.2%. It gets a good specific recognition ability and potential practical application value.
关键词： reverse microemulsion method,molecular imprinting technology,sulfadimidine,CdTe quantum dots,fluorescence sensor
更新于2025-09-12 10:27:22
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A colorimetric sensor array for recognition of 32 Chinese traditional cereal vinegars based on “turn-off/on” fluorescence of acid-sensitive quantum dots
摘要： Colorimetric sensor array is a sensitive, rapid, and inexpensive detection technology which simulates human olfaction system based on various organic dyes. In this work, a sensor array based on acid-sensitive CdTe QDs coupled with chemometrics method was developed and proved to be a rapid, accurate and sensitive method for identification of 32 kinds of Chinese traditional cereal vinegars (CTCV). The specificity of identification of this method was mainly depends on the organic acids and melanoidins of CTCV. Among them, organic acids can quench the fluorescence of QDs through enhancing their electron transfer (hydrogen bond) and resonance energy transfer, and the fluorescence intensity of melanoidin was closely related to the brewing technology and aging year of CTCV. The types and aging time of 32 CTCV can be 100% identified at a dilution of 1000 by partial least squares discriminant analysis, when the latent variables were 4. And only one kind of QDs is needed instead of various organic dyes to this kind of colorimetric sensor array. Except for vinegar, this method can also be used in the identification of other food which rich in organic acid.
关键词： Chemometrics,Chinese traditional cereal vinegars,Fluorescence sensors,CdTe quantum dots,Organic acid
更新于2025-09-12 10:27:22
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Anomalous Stokes shift of colloidal quantum dots and their influence on solar cell performance
摘要： We report an anomalous Stokes shift effect observed in colloidal solutions containing down-shifting Carbon quantum dots (CQDs) of different sizes that is expected to have a positive in?uence on the power conversion ef?ciency of photovoltaic structures. Speci?cally, with an excitation wavelength of 390 nm, individual colloidal solutions of CQDs whose diameter was determined by the applied current during synthesis, exhibited photoluminescent (PL) emission wavelength peaks centered at 420 nm. However, the colloidal solution comprising the mixture of all the previously synthesized CQDs of different diameters was observed to have an anomalous PL Stokes shift centered at 515 nm. Furthermore, the afore-mentioned anomalous SSE was also observed in CdTe QDs when added to the CQD mixed-solution (CMS). Thus, whereas a mixture of CdTe QDs of different sizes, exhibited a down-shifted photoluminescence centered at 555 nm, the peak was observed to have an anomalous Stokes shift centered at 580 nm when combined with the CMS. Quantum dot characterization included crystal structure analysis as well as photon absorption and photoluminescence wavelengths. Subsequently, the synthesized QDs were dispersed in a polymeric layer of PMMA and incorporated on functional and previously characterized solar cells, to quantify their in?uence in the electrical performance of the photovoltaic devices. The observations indicate an improvement in the PCE of 4.6% when incorporating Carbon QDs, 2.9% with CdTe QDs and 4.8% when employing both C and CdTe QDs.
关键词： solar cell performance,photoluminescence,Carbon quantum dots,Anomalous Stokes shift,colloidal quantum dots,CdTe quantum dots,power conversion efficiency
更新于2025-09-11 14:15:04