Surface Of QDs Research Articles

Ultrasensitive determination of mercury ions (Ⅱ) by analysis of the degree of quantum dots aggregation

In this work, an ultrasensitive fluorescence strategy on counting the degree of aggregation (DOA) of QDs aggregates was developed for Hg2+ detection, which is based on thymine-Hg2+-thymine (T-Hg2+-T) coordination chemistry. Oligonucleotides containing 12 thymines are modified on the surface of QDs which could protect QDs effectively from aggregation in the absence of Hg2+. While in the presence of Hg2+, QDs will be made to attach with each other by the structure of “T-Hg2+-T” formed, and then aggregated in the sensing system. The DOA is acquired easily by recording the entire process of the blue shifting and photobleaching of QDs aggregates. First-order spectrum of each QD in the aggregates can be released from the original overlapped spectral image of the aggregates in sequence under continuous illumination because QDs exhibit the asynchronous spectra blue shifting. Employed 0.3 nM functional QDs in the sensing system, an ultralow detection limit of 4.6 pM was reached by the counting DOA-based sensing strategy. Besides, the sensor also shows high selectivity against other 12 metal ions even at high concentrations. At last, the application of the sensing strategy for river water shows that the real samples can be worked well using this method.

FRET from ZnSe/ZnS QDs to coumarin dyes: Role of acceptor dipole moment and QD surface states on FRET efficiency

Herein we report efficient fluorescence resonance energy transfer (FRET) between heavy metal free core-shell ZnSe/ZnS quantum dots (QDs as donors) and coumarin 540A (C540A), coumarin 515 (C515) and coumarin 519 (C519) laser dyes (as acceptors) using multiple spectroscopic techniques which interestingly provides a strong evidence for its dependence on acceptor dipole moment. The results also reveal that the coumarin dye acceptors, especially the C519 probe, significantly quench the photoluminescence intensity of QDs. Remarkably high energy transfer efficiencies ~ 85% in the QDs-C519 FRET pairs are noted which demonstrate that acceptor dipole moment could be associated with energy transfer via strong electrostatic dipole-dipole interaction. The FRET efficiency was investigated as function of QDs size and surface chemistry conditions. Interestingly, the nonlinear dependence of FRET efficiency on the spectral overlap was observed contradictory to the Förster's theory. This nonlinearity might be due to role of QDs surface states and acceptor dipole moment. The current work is not only expected to provide useful information about the interaction between inorganic and organic hetero-structured probes via FRET mechanism but also throws light on the role of acceptor dipole moment, surface states in addition to nonlinear dependence of transfer efficiency on spectral overlap.

Efficient and Stable CsPbBr3 Quantum-Dot Powders Passivated and Encapsulated with a Mixed Silicon Nitride and Silicon Oxide Inorganic Polymer Matrix.

Despite the excellent optical features of fully inorganic cesium lead halide (CsPbX3) perovskite quantum dots (PeQDs), their unstable nature has limited their use in various optoelectronic devices. To mitigate the instability issues of PeQDs, we demonstrate the roles of dual-silicon nitride and silicon oxide ligands of the polysilazane (PSZ) inorganic polymer to passivate the surface defects and form a barrier layer coated onto green CsPbBr3 QDs to maintain the high photoluminescence quantum yield (PLQY) and improve the environmental stability. The mixed SiN x/SiN xO y/SiO y passivated and encapsulated CsPbBr3/PSZ core/shell composite can be prepared by a simple hydrolysis reaction involving the addition of adding PSZ as a precursor and a slight amount of water into a colloidal CsPbBr3 QD solution. The degree of the moisture-induced hydrolysis reaction of PSZ can affect the compositional ratio of SiN x, SiN xO y, and SiO y liganded to the surfaces of the CsPbBr3 QDs to optimize the PLQY and the stability of CsPbBr3/PSZ core/shell composite, which shows a high PLQY (∼81.7%) with improved thermal, photo, air, and humidity stability as well under coarse conditions where the performance of CsPbBr3 QDs typically deteriorate. To evaluate the suitability of the application of the CsPbBr3/PSZ powder to down-converted white-light-emitting diodes (DC-WLEDs) as the backlight of a liquid crystal display (LCD), we fabricated an on-package type of tricolor-WLED by mixing the as-synthesized green CsPbBr3/PSZ composite powder with red K2SiF6:Mn4+ phosphor powder and a poly(methyl methacrylate)-encapsulating binder and coating this mixed paste onto a cup-type blue LED. The fabricated WLED show high luminous efficacy of 138.6 lm/W (EQE = 51.4%) and a wide color gamut of 128% and 111% without and with color filters, respectively, at a correlated color temperature of 6762 K.

CuInS2 quantum dot sensitized solar cells with high VOC ≈ 0.9 V achieved using microsphere-nanoparticulate TiO2 composite photoanode

CuInS2 (CIS) based solar cell devices are fabricated by sensitizing TiO2 photoanodes with CIS quantum dots (CIS-QDs). Morphologically different TiO2, viz. Degussa P25 nanoparticles, smooth and fibrous microspheres (SμS and FμS respectively) are used to fabricate photoanodes. CIS-QDs are synthesized using dodecanethiol (DDT), CuI and In(OAc)3 precursors by solvothermal method. DDT surfactant present on the CIS QDs surface is replaced with 3-mercaptopropionic acid in a single phase one step procedure to enable efficient loading of QDs onto photoanode and as linker molecule for charge carrier extraction. The CIS QDs sensitized on SμS and FμS microsphere photoanode layers exhibit a photoconversion efficiency (η) of 3.2% and 1.6%, respectively, in comparison to η ≈ 2.1% for nanoparticulate TiO2 (Degussa P25). Further increase in efficiency is obtained (3.8% for SμS and 2.5% for FμS) when composite photoanode films made of porous microspheres filled with nanoparticulate P25 are used. A maximum efficiency of 3.8% (with JSC ≈ 6.2mA, VOC ≈ 926mV and FF ≈ 66 for cell area ≈ 0.25cm2 and thickness ≈ 20µm) is realized when 4.6nm CIS QDs sensitized on composite photoanode (consisting of 80wt. % SμS and 20wt. % P25) is used. High VOC observed is unprecedented and is possible due to combined effect of SμS+P25 composite photoanode properties such as fewer defects, good connectivity between particles, effective light scattering, minimum recombination, and effective electron transport and size optimized CuInS2 QDs. Electrochemical impedance spectroscopy studies reveal a low interfacial resistance and longer electron life time in SμS+P25 composite photoanodes.

Light-Emitting Diodes Based on Colloidal Silicon Quantum Dots with Octyl and Phenylpropyl Ligands.

Colloidal silicon quantum dots (Si QDs) hold ever-growing promise for the development of novel optoelectronic devices such as light-emitting diodes (LEDs). Although it has been proposed that ligands at the surface of colloidal Si QDs may significantly impact the performance of LEDs based on colloidal Si QDs, little systematic work has been carried out to compare the performance of LEDs that are fabricated using colloidal Si QDs with different ligands. Here, colloidal Si QDs with rather short octyl ligands (Octyl-Si QDs) and phenylpropyl ligands (PhPr-Si QDs) are employed for the fabrication of LEDs. It is found that the optical power density of PhPr-Si QD LEDs is larger than that of Octyl-Si QD LEDs. This is due to the fact that the surface of PhPr-Si QDs is more oxidized and less defective than that of Octyl-Si QDs. Moreover, the benzene rings of phenylpropyl ligands significantly enhance the electron transport of QD LEDs. It is interesting that the external quantum efficiency (EQE) of PhPr-Si QD LEDs is lower than that of Octyl-Si QD LEDs because the benzene rings of phenylpropyl ligands suppress the hole transport of QD LEDs. The unbalance between the electron and hole injection in PhPr-Si QD LEDs is more serious than that in Octyl-Si QD LEDs. The currently obtained highest optical power density of ∼0.64 mW/cm2 from PhPr-Si QD LEDs and highest EQE of ∼6.2% from Octyl-Si QD LEDs should encourage efforts to further advance the development of high-performance optoelectronic devices based on colloidal Si QDs.

Single molecule localization imaging of exosomes using blinking silicon quantum dots

Discovering new fluorophores, which are suitable for single molecule localization microscopy (SMLM) is important for promoting the applications of SMLM in biological or material sciences. Here, we found that silicon quantum dots (Si QDs) possess a fluorescence blinking behavior, making them an excellent candidate for SMLM. The Si QDs are fabricated using a facile microwave-assisted method. Blinking of Si QDs is confirmed by single particle fluorescence measurement and the spatial resolution achieved is about 30 nm. To explore the potential application of Si QDs as the nanoprobes for SMLM imaging, cell derived exosomes are chosen as the object owing to their small size (50–100 nm in diameter). Since CD63 is commonly presented on the membrane of exosomes, CD63 aptamers are attached to the surface of Si QDs to form nanoprobes which can specifically recognize exosomes. SMLM imaging shows that Si QDs based nanoprobes can indeed realize super resolved optical imaging of exosomes. More importantly, blinking of Si QDs is observed in water or PBS buffer with no need for special imaging buffers. Besides, considering that silicon is highly biocompatible, Si QDs should have minimal cytotoxicity. These features make Si QDs quite suitable for SMLM applications especially for live cell imaging.

A rainbow ratiometric fluorescent sensor array on bacterial nanocellulose for visual discrimination of biothiols.

Considering the crucial role of biothiols in many biological processes, which turns them into highly valuable biomarkers for the early diagnosis of various diseases, the development of an affordable, sensitive and portable probe for the identification and discrimination of these compounds is of great importance. Herein, we developed a ratiometric fluorescent (RF) sensor array with a wide color emissive variation, on a bacterial cellulose (BC) nanopaper substrate for the visual discrimination of biothiols. To this aim, RF sensing elements including N-acetyl l-cysteine capped green CdTe quantum dots-rhodamine B (GQDs-RhB) and red CdTe QDs-carbon dots (RQDs-CDs) at two different NaOH concentrations (0 and 5 mM) were utilized as sensor elements for the discrimination of biothiols. Owing to the high affinity of the thiol group (SH) to the surface of CdTe QDs and the aggregation of the QDs, the fluorescence (FL) emission of the QDs changed while the emission of the CDs and rhodamine B remained almost unchanged upon the addition of biothiols. Accordingly, characteristic rainbow-like FL fingerprint patterns were created for each biothiol which were then distinguished both visually and spectroscopically. Hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA) pattern recognition techniques were employed for the identification and discrimination of biothiols. Based on the designed RF sensor array, convenient test strips were fabricated on BC nanopaper for the visual discrimination of biothiols. It has been shown that this probe can successfully identify biothiols in human plasma as well. Altogether, the developed nanopaper-based sensor array offers an efficient biothiol discrimination tool that can be potentially exploited in the near future in theranostic and point-of-care applications.

Facile fabrication of tungsten disulfide quantum dots (WS2 QDs) as effective probes for fluorescence detection of dopamine (DA)

Through the simple liquid exfoliation method, WS2 QDs show excellent fluorescent properties. DA could form thin on the surface of WS2 QDs through the polymerization effect, leading to quenching of fluorescence. The sensing system is highly selective for DA and the limit of detection is 3.3 μM. These results indicate that WS2 QDs are potentially applicable in optical imaging, catalysis and fluorescence sensing. The strategy might be suitable for the detection of other catecholamine.

Impact of vertical inter-QDs spacing correlation with the strain energy in a coupled bilayer quantum dot heterostructure

This study investigates the vertical inter-QDs spacing (VIDS) in a coupled bilayer quantum dots (CBQD) heterostructure using cross-sectional High Resolution Transmission Electron Microscopy (HRTEM). Simultaneously, we also examined the interrelationship of VIDS with the strain energy inside the CBQD stack. As a continuation, the CBQD heterostructure were further explored from different aspects of growth parameters, such as the deposition of ultrathin GaAs spacer layer of 4.0–4.5 nm between the seed and active layer of QDs, the effect of larger monolayer coverage (3.2 ML) of seed layer QDs, and the optimization of growth rates for the CBQDs. Moreover, we present a model technique to characterize the in-plane 2θχ/Φ of InAs QDs and GaAs at (002) and (004) planes in order to analyze the strain. This study was the first of its kind to look at the formation of self-assembled In(x)Ga(1-x)As layer at the interface across the ultrathin GaAs spacer and InAs QDs, verified with HRTEM images. Smaller size of QDs formed in the seed layer led to the formation of a non-uniform self-assembled In(x)Ga(1-x)As layer. The problem of non-uniformity of In(x)Ga(1-x)As layer was resolved by increasing the seed layer monolayer coverage from 2.5 to 3.2 ML. The percentage of gallium adatoms inter-diffused into the outer surface of InAs QDs to form the self-assembled In(x)Ga(1-x)As layer was ∼31% for VIDS ∼1.4 ± 2 nm.

Selective phosphorescence sensing of pesticide based on the inhibition of silver(I) quenched ZnS:Mn2+ quantum dots

Pesticides abuse has drawn considerable attention in agriculture, environment and food safety in recent years. How to selective and on-site detection of pesticide residues with rapid operation and low cost is still a hot topic. In this work, we report a novel method for the detection of pesticide thiram using phosphorescent Mn-doped ZnS quantum dots (ZnS:Mn2+ QDs) combined by an affinity reaction between thiram and Ag+ ions. On the one hand, the phosphorescence of as-prepared ZnS:Mn2+ QDs at 590nm can be effectively quenched by Ag+ ions due to the direct cation-exchange reaction at the surface of QDs. On the other hand, the presence of thiram can inhibit phosphorescence quenching through the formation of stable Ag-thiram complex. This inhibition resulted in a linear recovery in emission intensity with increasing the amount of thiram, which enables thiram residues to be identified under the UV light illumination. In buffer condition, thiram could be detected within the concentration range of 50nM–2.5μM with a detection limit of 25nM. Moreover, the proposed method has been successfully applied to thiram residues identification at fresh fruit peels. The investigation provides a profile for instant and visual detection of surface residues using doped quantum dots.

Spectroscopic studies on the interaction between thioglycolic acid (TGA)- capped CdTe quantum dots and cyanine dyes

Three different particle sizes from cadmium telluride semiconductor quantum dots (CdTe QDs)have been prepared using thioglycolic acid as a capping agent in aqueous media. The photophysical behaviorfor these particles has been studied in presence of monomethine dyes belong to thiazole orange (TO) family.The aggregation of the cyanine dyes on QDs surface was attributed to the presence of electrostatic attractionbetween negatively charged thioglycolic capping molecules and the ionic dye. Energy transfer process fromCdTe QDs to cyanine dyes was also studied using electronic absorption and steady state emissionmeasurements. The energy transfer parameters such as Stern- Volmer rate constants Ksv, binding sites n,quenching sphere radius r, critical energy transfer distance R0 and the efficiency of energy transfer E, havebeen calculated. The enhancement in the triplet state emission and absorption for the studied dye in thepresence of QDs was expected to play a role in molecular oxygen sensitization and photodynamic therapy(PDT) as well as photovoltaic applications.

A fluorescent sensing for glycoproteins based on the FRET between quantum dots and Au nanoparticles

A simple fluorescent probe based on fluorescence resonance energy transfer (FRET) between the glucosamine-Mn-doped ZnS QDs and mercaptophenylboronic acid (MBA)-capped AuNPs was designed for the determination of glycoproteins such as immunoglobulin G (IgG), transferrin (Trf), α1-acid glycoprotein (AGP) and horseradish peroxidase (HRP). The FRET process took place via interaction between the glucosamine on the surface of QDs and boronic acid moieties on AuNPs surface, and resulted in the fluorescence quenched of the QDs. The FRET efficiency from QDs to AuNPs was calculated to be 75.4%. However, the FRET process would be inhibited after glycoproteins were introduced into the QDs-AuNPs system. The stronger interaction between the MBA on the surface of AuNPs and glycoproteins would keep the AuNPs far away from the QDs surface, leading to the fluorescence recovered of the QDs. The as-prepared sensor showed a high sensitivity and selectivity for glycoproteins. The dissociation constants and the detection limits of the selected standard glycoproteins (Trf, HRP, IgG and AGP) were estimated to be around 10−7M and 10−9M, respectively. Finally, this sensor has been successfully used for the determination of the AGP in serum samples without any complicated pretreatment and the recovery was in the range of 70%–105%.

L-noradrenaline functionalized near-infrared fluorescence CdSeTe probe for the determination of urea and bioimaging of HepG2 Cells

In this paper, near-infrared (NIR) light emitting L-noradrenaline functionalized CdSeTe QDs (NA-CdSeTe) were synthesized and applied to the biosensing of urea. When the pH value of NA-CdSeTe solution was adjusted from neutral to alkalinity, the noradrenaline on the surface of QDs would turn to quinone, which triggered the fluorescence quenching of NA-CdSeTe probe due to the charge transfer interactions between QDs and the proximal quinone. Based on the fact that the hydrolysis of urea in the presence of urease would release OH− and slightly change the pH value of the solution, the fluorescence intensity of NA-CdSeTe QDs could be linked to the enzymatic degradation of urea. The novel urea-biosensing system could effectively determinate urea in the dynamic concentration range from 0.057 to 13mmol/L. Furthermore, NA-CdSeTe probe could serve as an “optical window” for the bioimaging of urea with high selectivity in the serum samples and HepG2 cells. The urea-bioimaging system could effectively probe urea in the dynamic concentration range from 0.2 to 5mmol/L. This NIR probe was excellent candidate not only for its sensitive with urea but also its real-time bioimaging. We expected that this NIR probe based strategy could pave the way for developing simple, no enzyme immobilization required and good sensitive method related detections for further medical applications.

Synthesis of surface molecular imprinting polymer on SiO2-coated CdTe quantum dots as sensor for selective detection of sulfadimidine

This paper demonstrates a facile method to synthesize surface molecular imprinting polymer (MIP) on SiO2-coated CdTe QDs for selective detection of sulfadimidine (SM2). The fluorescent MIP sensor was prepared using cadmium telluride quantum dots (CdTe QDs) as the material of fluorescent signal readout, sulfadimidine as template molecule, 3-aminopropyltriethoxysilane (APTES) as functional monomer and tetraethyloxysilane (TEOS) as cross-linking agent. The CdTe cores were embed in the silicon shells by a sol-gel reaction and then the molecular imprinting layers were immobilized on the surface of the SiO2-coated CdTe QDs. Under the optimized conditions, the relative fluorescent intensity weakened in a linear way with the increasing concentration of sulfadimidine in the range of 10–60μmolL−1. The practical application of the fluorescent MIP sensor was evaluated by means of analyzing sulfadimidine in the real milk samples. The recoveries were at the range of 90.3–99.6% and the relative standard deviation (RSD) ranged from 1.9 to 3.1%, which indicates the successful synthesis of the fluorescent MIP sensor. This sensor provides an alternative solution for selective determination of sulfadimidine from real milk samples.

Fluorescence enhancement of CdTe quantum dots by HBcAb-HRP for sensitive detection of H2O2 in human serum

A simple, high selective, ultra-sensitive and stable biosensor based on hepatitis B core antibody labeled with horseradish peroxidase (HBcAb-HRP) induced fluorescent enhancement of CdTe QDs for recognition of H2O2 have been constructed. In this assay, sulfurs in HBcAb-HRP, which possess a strong affinity towards Cd2+, can improve greatly the recombination fluorescence of CdTe QDs by creating more radiative centers at CdTe/Cd-SR complex. Then, H2O2 oxidizes Cd-S bonds in CdTe QDs to organic disulfide product (RS-SR), causing thioglycolic acid (TGA) and HBcAb-HRP detach from surface of CdTe QDs and thus leading to fluorescence quenching. Just with the addition of HBcAb-HRP, sensitivity of the new biosensor has been improved by near one order of magnitude as compared with CdTe QDs probe. Detection limit of HBcAb-HRP-CdTe QDs biosensor for determination of H2O2 was 6.9×10−8mol L−1 (3σ/slope), and the excellent linear range was 1.0×10−7~1.5×10−4molL−1. By using sodium diethyldithiocarbamate (DDTC) and NH4OH as masking agents of Ag+, Hg2+ and Cu2+, H2O2 can be selectively detected in coexistence with Ag+, Hg2+ and Cu2+, and the biosensor has been used to detect H2O2 in human serum with satisfactory results. The superior properties of this biosensor showed great potential usage in more chemical and biological researches.

A novel CdTe quantum dots probe amplified resonance light scattering signals to detect microRNA-122

We report a rapid and facile resonance light scattering (RLS) technique that utilizes CdTe quantum dots (CdTe QDs) probe to detect microRNA-122. The RLS sensor is ingeniously designed with P1 and P2, two cDNA sequence probes with partially complementary sequences to miRNA-122. The amine-modified P1 and P2 are coupled to the surface of QDs to form functional QDs-P1 and QDs-P2 conjugates, which are collectively referred to as QDs-P. The cDNAs hybridize with the target miRNA to rapidly induce the self-assembly of QDs probe and change RLS intensity. The proposed technique can detect miRNA-122 within 40min. RLS intensity is enhanced in proportion with miRNA-122 concentrations of 0.16–4.80nM and has a low detection limit of 9.4pM. In addition, the assay satisfactorily detects miRNAs in human serum samples. Thus, the assay has considerable potential for the analysis of other interesting tumor makers.

Surface defect modification of ZnO quantum dots based on rare earth acetylacetonate and their impacts on optical performance

The surface defect modification has an important effect on the application of ZnO quantum dots, and it has gained much progress in recently years, propelled by the development of additives. Our research efforts are directed toward developing a new surface modification additive RE(AcAc)3 (RE=Ce, Dy, Tb) to achieve fine ZnO QDs and adjust their surface properties. RE(AcAc)3/ZnO QDs nanostructured materials have been designed and prepared, and particular emphasis has been given to the relation between the surface modification and optical properties. The effects of RE(III) acetylacetonate modification on the FT-IR, TEM images and photoluminescence (PL) spectra were investigated, and the surface defect modification principle and effect were discussed in details. The band gap (Eg) was also calculated to prove the surface modification effect. For the RE(AcAc)3/ZnO QDs complex materials, stable linkage occurs because of the affinity of COOH from acetylacetonate anionic ligand to zinc oxide surfaces, with attachment to the zinc oxide by hydrogen bonding between the protons of the hydroxyl groups on the surface of ZnO QDs and the π–system of acetylacetone.

Quantification of gold(III) in solution and with a test stripe via the quenching of the fluorescence of molybdenum disulfide quantum dots

The paper describes a fluorescent method for determination of Au(III) using molybdenum disulfide quantum dots (MoS2 QDs) that were prepared by a hydrothermal route using glutathione as a reductant. The photoluminescence of MoS2 QDs peaks at 416 nm if excited at 340 nm and is temporally stable even in presence of NaCl or when stored in the refrigerator for one year. Its quantum yield is 12.7 %. The blue-green fluorescence of MoS2 QDs is fairly specifically quenched by Au(III) ions and therefore presents a useful nanoprobe for this ion. Fluorescence intensity drops linearly with the concentration of Au(III) in the range from 0.5 to 1000 μM, and the lower detection limit is 64 nM. The quenching mechanism was investigated and it is concluded that the process is due to the reduction of Au(III) and the deposition of Au(0) on the surface of the MoS2 QDs. The nanoprobe was successfully applied to the determination of Au(III) in (spiked) environmental samples. A test stripe for Au(III) was obtained by soaking a piece of paper with a colloidal solution of the MoS2 QDs, and it was found that this stripe, after drying, can also be used to quantify Au(III) via fluorescence.

A facile single injection Hydrothermal method for the synthesis of thiol capped CdTe Quantum dots as light harvesters

A facile, Single Injection Hydrothermal (SIH) method has been developed to synthesize high quality 3-Mercaptopropionic Acid (MPA) stabilized aqueous CdTe QDs, entirely in ambient environment. The synthesis protocol eliminates the use of inert atmosphere for reducing elemental Tellurium powder to Te precursor avoiding the oxidation of Te powder. The XRD result revealed that the synthesized QDs are in cubic zincblende type crystalline structure, without signature of Te oxidation. FTIR spectra have confirmed the attachment of short chained organic compound MPA to the surface of QDs by covalent bond. The Quantum confinement effect was clearly evident by shift in Longitudinal Optic (LO) peak of Raman spectra and absorption peak wavelength with respect to bulk CdTe materials. The optical direct band gap energy of CdTe QDs is between 3.63eV to 1.96eV and QDs size below 6nm, confirm the QDs are well under strong Quantum confinement regime. Also, photoluminescence spectra depict a stable and high luminescence emission from green to dark red color. All these results corroborate that the synthesis of CdTe QDs procedure is very advantageous and present a simple, economical and easily up scalable method for large scale production.

Photo-induced interaction of thioglycolic acid (TGA)-capped CdTe quantum dots with cyanine dyes

The photo-induced interaction of three different sizes of thioglycolic acid (TGA)-capped CdTe quantum dots (CdTe QDs) with two monomethine cyanine dyes belonging to the thiazole orange (TO) family has been studied. Positively charged cyanines interact with QDs surface which is negatively charged due to capping agent carboxylate ions. The energy transfer parameters including Stern-Volmer constant, Ksv, number of binding sites, n, quenching sphere radius, r, the critical energy transfer distance, R0, and energy transfer efficiencies, E have been calculated. The effect of structure and the number of aggregating molecules have been studied as a function of CdTe QDs particle size. Combining organic and inorganic semiconductors leads to increase of the effective absorption cross section of the QDs which can be utilized in novel nanoscale designs for light-emitting, photovoltaic and sensor applications. A synthesized triplet emission of the studied dyes was observed using CdTe QDs as donors and this is expected to play a potential role in molecular oxygen sensitization and in photodynamic therapy (PDT) applications.