Quantum Dot Emission Research Articles

A Selective Fluorescent Nanoprobe Based on Graphene Quantum Dots and Hg2+ for the Determination of Tetracycline in Biological Samples.

A simple, sensitive, and selective fluorometric method based on graphene quantum dots and Hg2+ is presented for the determination of tetracycline. The fluorescence emission of graphene quantum dots at 463nm decreased in the presence of Hg2+ ions due to its electrostatic interaction with the negatively charged surface of quantum dots at pH = 8.0. The addition of tetracycline to this system resulted in the retrieval of the fluorescence emission of the graphene quantum dots proportional to the tetracycline concentration. This is because of the interaction between tetracycline and Hg2+ that results in the release of the quantum dots' surface. Under the optimized conditions, the calibration curve indicated good linearity in the range of 2.0-44.0nmol L-1 with a detection limit of 0.52nmol L-1 for tetracycline. The designed nanoprobe was capable of the determination of tetracycline in serum and urine samples.

Coherent THz wave emission from HgTe quantum dots

Mercury telluride (HgTe) nanocrystals (NCs) are very promising for THz technology as they exhibit broad THz absorption resonances and a carrier lifetime of a few picoseconds as well as being easily fabricated using solution synthesis. In this work, we show their light emission properties in the THz spectral range, up until now unexplored, and show how THz pulse generation can be used for microscopic insights into these NCs. In particular, we report on coherent THz emission from large HgTe NCs excited by linearly polarized optical pulses via second-order nonlinear effects. The peak emission frequency is tunable from 0.4 to 0.8 THz by varying incident angles of optical pulses from 0° to 45°. Our results reveal that the THz emission is induced by transient photocurrents arising from both photogalvanic and photon drag effects. By pushing the light emission of colloidal quantum dots down to the THz spectral range, our study expands the application fields of NCs, especially toward the development of easily integrable and tunable THz emitters and quantum THz devices.

High efficiency pure blue perovskite quantum dot light-emitting diodes based on formamidinium manipulating carrier dynamics and electron state filling

Achieving high efficiency and stable pure blue colloidal perovskite quantum dot (QD) light-emitting diodes (LEDs) is still an enormous challenge because blue emitters typically exhibit high defect density, low photoluminescence quantum yield (PLQY) and easy phase dissociation. Herein, an organic cation composition modification strategy is used to synthesize high-performance pure blue perovskite quantum dots at room temperature. The synthesized FA-CsPb(Cl0.5Br0.5)3 QDs show a bright photoluminescence with a high PLQY (65%), which is 6 times higher than the undoped samples. In addition, the photophysical properties of the FA cation doping was deeply illustrated through carrier dynamics and first principal calculation, which show lower defects, longer lifetime, and more reasonable band gap structure than undoped emitters. Consequently, pure blue FA-CsPb(Cl0.5Br0.5)3 QDs light-emitting devices were fabricated and presented a maximum luminance of 1452 cd m−2, and an external quantum efficiency of 5.01 % with an emission at 474 nm. The excellent photoelectric properties mainly originate from the enhanced blue QDs emitter and effective charge injection and exciton radiation. Our finding underscores this easy and feasible room temperature doping approach as an alternative strategy to blue perovskite QD LED development.

Deterministic Quantum Light Arrays from Giant Silica-Shelled Quantum Dots.

Colloidal quantum dots (QDs) are promising candidates for single-photon sources with applications in photonic quantum information technologies. Developing practical photonic quantum devices with colloidal materials, however, requires scalable deterministic placement of stable single QD emitters. In this work, we describe a method to exploit QD size to facilitate deterministic positioning of single QDs into large arrays while maintaining their photostability and single-photon emission properties. CdSe/CdS core/shell QDs were encapsulated in silica to both increase their physical size without perturbing their quantum-confined emission and enhance their photostability. These giant QDs were then precisely positioned into ordered arrays using template-assisted self-assembly with a 75% yield for single QDs. We show that the QDs before and after assembly exhibit antibunching behavior at room temperature and their optical properties are retained after an extended period of time. Together, this bottom-up synthetic approach via silica shelling and the robust template-assisted self-assembly offer a unique strategy to produce scalable quantum photonics platforms using colloidal QDs as single-photon emitters.

CdSe quantum dot formation induced by electron beam irradiation

The formation of quantum dots (QDs) induced by electron beam irradiation onto a highly strained CdSe layer on ZnSe (001) is investigated. In situ reflection high-energy electron diffraction is used for dual purposes: QD formation by electron beam irradiation and monitoring the progress of surface morphology. QD formation is confirmed by observation of nanoscale three-dimensional islands using transmission electron microscopy. It is also verified by imaging of an isolated single QD emission at room temperature by photoluminescence microscopy. Electron beam irradiation increases QD size both in height and lateral directions, resulting in the shift of emission from green to yellow spectral region.

Progress and Prospects of Nanoscale Emitter Technology for AR/VR Displays

AbstractAugmented reality (AR) and virtual reality (VR) are emerging interactive technologies that realize the “metaverse,” leading to a totally new digital interactive experience in daily life in various aspects. In order to provide users with a more immersive experience, displays for AR/VR have rapidly evolved to achieve high resolutions and a large color gamut on small panels. Recently, nanoscale light emitters such as quantum dots (QDs) and metal halide perovskites (MHPs) with high photoluminescence quantum efficiency and color purity levels have garnered much attention as color conversion materials in AR/VR displays. However, the low material stability and the absence of a high‐resolution patterning process that does not impair the optical properties of nanoscale emitters act as obstacles preventing the realization of high‐resolution AR/VR displays. Herein, the state‐of‐the‐art technologies constituting current AR/VR devices are reviewed from an industrial point of view and the recent progress in QD and MHP emitter technologies are discussed, including their basic structural properties, synthesis strategies to enhance the stability, advanced patterning technologies, down‐conversion and light‐emitting diode applications. Based on the review, the authors’ perspective on future research directions of nanoscale emitters for next‐generation AR/VR displays is presented.

Enhanced amplified spontaneous emission of CsPbBr3 quantum dots via gold nanorods-induced localized surface plasmon resonance

Incorporating metallic nanostructures into a cesium lead halide [CsPbX3 (X = Cl, Br, I)] perovskite system has attracted considerable attention for improving the performance of amplified spontaneous emission (ASE) and lasing. However, the ASE/lasing threshold is normally quite high since the photophysical properties of pristine CsPbX3 quantum dots (QDs) are limited and the traditionally utilized metal nanoparticles suffer from a weak localized surface plasmon resonance within a narrow spectral range. Herein, a configuration of a silica coated CsPbBr3 QDs (CsPbBr3@SiO2 QDs) film incorporated with the deposition of gold nanorods (AuNRs) underneath has been proposed for high-performance ASE. In this configuration, SiO2 coating not only serves as an insulation layer to avoid the large Ohmic loss between CsPbBr3 and Au but also contributes to improved photoluminescence quantum yield and stability against water, heat, and ultraviolet light compared to the counterparts of pristine CsPbBr3 QDs. As a result, the fabricated CsPbBr3@SiO2-AuNRs hybrid film yields a low-threshold ASE (23.6 μJ/cm2) with excellent photostability owing to efficient exciton–plasmon coupling effect, which is only 23% of the pristine CsPbBr3 QDs film (102 μJ/cm2). The demonstration of metallic NRs coupled perovskite QDs not only provides a strategy for realizing strong light–matter interactions but also paves the way for improving the performance of perovskite-based optoelectronic devices.

Hybrid Nucleic Acid-Quantum Dot Assemblies as Multiplexed Reporter Platforms for Cell-Free Transcription Translation-Based Biosensors.

Cell-free synthetic biology has emerged as a valuable tool for the development of rapid, portable biosensors that can be readily transported in the freeze-dried form to the point of need eliminating cold chain requirements. One of the challenges associated with cell-free sensors is the ability to simultaneously detect multiple analytes within a single reaction due to the availability of a limited set of fluorescent and colorimetric reporters. To potentially provide multiplexing capabilities to cell-free biosensors, we designed a modular semiconductor quantum dot (QD)-based reporter platform that is plugged in downstream of the transcription-translation functionality in the cell-free reaction and which converts enzymatic activity in the reaction into distinct optical signals. We demonstrate proof of concept by converting restriction enzyme activity, utilized as our prototypical sensing output, into optical changes across several distinct spectral output channels that all use a common excitation wavelength. These hybrid Förster resonance energy transfer (FRET)-based QD peptide PNA-DNA-Dye reporters (QD-PDDs) are completely self-assembled and consist of differentially emissive QD donors paired to a dye-acceptor displayed on a unique DNA encoding a given enzyme's cleavage site. Three QD-based PDDs, independently activated by the enzymes BamHI, EcoRI, and NcoI, were prototyped in mixed enzyme assays where all three demonstrated the ability to convert enzymatic activity into fluorescent output. Simultaneous monitoring of each of the three paired QD-donor dye-acceptor spectral channels in cell-free biosensing reactions supplemented with added linear genes encoding each enzyme confirmed robust multiplexing capabilities for at least two enzymes when co-expressed. The modular QD-PDDs are easily adapted to respond to other restriction enzymes or even proteases if desired.

Effective Blue Light-Absorbing AuAg Nanoparticles in InP Quantum Dots-Based Color Conversion.

In typical color-by-blue mode-based quantum dot (QD) display devices, only part of the blue excitation light is absorbed by QD emitters, thus it is accompanied by the leakage of blue light through the devices. To address this issue, we offer, for the first time, the applicability of AuAg alloy nanoparticles (NPs) as effective blue light absorbers in InP QD-based color-by-blue platforms. For this, high-quality fluorescent green and red InP QDs with a double shell scheme of ZnSe/ZnS were synthesized and embedded in a transparent polymer film. Separately, a series of Au/Ag ratio-varied AuAg NPs with tunable plasmonic absorption peaks were synthesized. Among them, AuAg NPs possessing the most appropriate absorption peak with respect to spectral overlap with blue emission are chosen for the subsequent preparation of AuAg NP polymeric films with varied NP concentrations. A stack of AuAg NP polymeric film on top of InP QD film is then placed remotely on a blue light-emitting diode, successfully resulting in systematically progressive suppression of blue light leakage with increasing AuAg NP concentration. Furthermore, the beneficial function of the AuAg NP polymeric overlayer in mitigating undesirable QD excitation upon exposure to ambient lights was further examined.

Reviving aged CsPbBr3 quantum dots by triallylamine etching

All-inorganic halide perovskite quantum dots are widely known to suffer luminescence degradation owing to their intrinsic instability in atmospheric circumstances. Their high surface energy and weak internal ionic bonding could result in quantum dot agglomeration and structural degradation. In this work, we demonstrate that triallylamine is an efficient recovery agent to reignite the luminescence emission of aged CsPbBr3 quantum dots. The aged CsPbBr3 quantum dots re-emit bright green light instantly after triallylamine etching. The X-ray photoelectron spectroscopy results indicate a noticeable decrease of surface under-coordinated Pb ions content, leading to surface re-healing and photoluminescence quantum yields increasing. The unique emission recovery could reveal the details of CsPbBr3 quantum dot surface variety and facilitate the development of perovskite quantum dot display devices.

On-chip generation and dynamic piezo-optomechanical rotation of single photons

Integrated photonic circuits are key components for photonic quantum technologies and for the implementation of chip-based quantum devices. Future applications demand flexible architectures to overcome common limitations of many current devices, for instance the lack of tuneabilty or built-in quantum light sources. Here, we report on a dynamically reconfigurable integrated photonic circuit comprising integrated quantum dots (QDs), a Mach-Zehnder interferometer (MZI) and surface acoustic wave (SAW) transducers directly fabricated on a monolithic semiconductor platform. We demonstrate on-chip single photon generation by the QD and its sub-nanosecond dynamic on-chip control. Two independently applied SAWs piezo-optomechanically rotate the single photon in the MZI or spectrally modulate the QD emission wavelength. In the MZI, SAWs imprint a time-dependent optical phase and modulate the qubit rotation to the output superposition state. This enables dynamic single photon routing with frequencies exceeding one gigahertz. Finally, the combination of the dynamic single photon control and spectral tuning of the QD realizes wavelength multiplexing of the input photon state and demultiplexing it at the output. Our approach is scalable to multi-component integrated quantum photonic circuits and is compatible with hybrid photonic architectures and other key components for instance photonic resonators or on-chip detectors.

On the Molecular Origin of the Red Emission in the Newly Synthesized Carbon‐Based Quantum Dots

AbstractCarbon‐based quantum dots (QDs) represent a new family of luminescent nanomaterials with intriguing emission properties. They are synthesized predominately with the emission in the blue and green region of the visible spectrum, with limited success in producing red emission. Furthermore, the current literature on the subject lacks consensus with respect to the morphology of QDs. Contrary to their semiconductor counterparts, the data on the structure of fluorescing centers is scarce. Herein, we describe a facile one‐pot synthesis of red emissive QDs using citric acid and formamide as precursors without addition of any other source of nitrogen. The photophysical properties of the synthesized species were investigated by steady state and transient absorption and fluorescence spectroscopy. Some structural peculiarities were revealed using fluorescence correlation spectroscopy. Our findings show that the newly synthesized carbon‐based QDs, at least their emissive centers, are not part of nanoparticles but rather resemble small organic fluorophores. Furthermore, we have not eliminated the possibility that multiple fluorophores with different emission properties may be embedded within a single molecular entity.

Enzyme-free fluorescence determination of uric acid by combining CdTe quantum dots with metal-organic framework for signal amplification.

Thecomposite of CdTe quantum dots (QDs) with ZIF-8 was elaborately designed and synthesized as an enzyme-free fluorescent probe for the sensitive determination of uric acid (UA), based on the fluorescence detection property of CdTe QDs and the signal amplification function of ZIF-8. The structure and feature of the composite were characterized with transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, and fluorescence spectrometry. With adding UA to the composite, the emission of CdTe QDs reduced due to the inner filter anddynamic quenching effects of UA, and the adsorption ability of ZIF-8 toward UA promoted the response signal of CdTe QDs. On this basis, UA was quantified by the composite in the concentration range 0.05 to 10μM with excitation/emission wavelength at 287/615nm, and the detection limit of the composite toward UA was 32nM. The reproducibility of the composite for determining UA was further evaluated, and the relative standard deviations were below 10.2%. The composite also exhibited the merits of enzyme-free analysis such as low testing cost, short analysis time (1min), and loose pH condition (application in whole physiological pH range, 5.0 - 8.0). The composite was applied to thedetermination of UA in human urine with recoveries of spiked samplesin the range 99 to 113%.

Investigation on carrier injection tailoring and electroluminescence of WSe2 quantum dots in light-emitting diodes

WSe2 quantum dots (QDs) with exceptional properties are facilely synthesized with liquid phase exfoliation and hydrothermal reaction, and characterized with scanning electron microscope, atomic force microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The WSe2 QDs show good film morphology and effective carrier injection tailoring. Using 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as emitter, the near ultraviolet organic light-emitting diodes (NUV OLEDs) show maximum radiance of 1.25 mW/cm2 and external quantum efficiency (EQE) of 0.48% in inverted device with WSe2 QDs tailoring electron injection. The corresponding normal UV OLEDs show maximum radiance of 1.82 mW/cm2 and EQE of 1.39% with WSe2 QDs tailoring hole injection. Impedance spectroscopy analysis clarifies carrier injection tunability of WSe2 QDs. LEDs using WSe2 QDs as emitter are pioneeringly fabricated, showing maximum luminance of 426 cd/m2, EQE of 0.39%, luminous efficiency of 0.3 cd/A, power efficiency of 0.13 lm/W, and voltage dependent electroluminescent spectra. Ours results pave an alternative approach for interface modification, developing novel WSe2 QDs emitters, and boosting WSe2 QDs applications.

Novel Design of 0D Nanoparticles-2D Transition-Metal Dichalcogenides Heterostructured Devices for High-Performance Optical and Gas-Sensing Applications

Two-dimensional Transition metal dichalcogenides (TMDCs), have now attracted much attention due to their unique layered structure and physical properties. Up to date, several studies have demonstrated monolayered and few-layered TMDC-based photodetectors with good stability, photo-switching time and broadband detectivity from UV to infrared light region. However, the reported responsivity is not as high as the theoretical expectation, indicating that the light absorption is limited by the atomic thickness of 2D-TMDCs and could still be improved. To overcome the drawback of low absorption in 2D TMDC materials, previous reports have revealed several strategies to enhance the electric field and light-harvesting in these atomically thin TMDC layers by hybridizing plasmonic noble-metal nanoparticles, such as Pt, Au and Ag, to facilitate the light-matter interaction at the surface of semiconductors. In this regard, we aim to combine highly absorptive CuInS2(CIS) nanocrystals with noble metal nanoparticles as the photosensitizer to enhance the intrinsic absorptivity and promote the performance of MoS2-based photodetectors. The interests of noble nanocrystals such as platinum and gold are featured for their distinctive properties of the carrier transportation and the storage when combined with semiconductor materials. The strategy described here acts as a perspective to significantly improve the performance of MoS2-based photodetectors with outstanding detection responsivity with selectable wavelengths by further controlling the size and material of the decorated CIS nanocrystals.In addition to optical sensing, TMDCs have also been developed as a promising candidate for gas-molecule detection. Different from commercial metal oxide gas sensors, TMDCs as sensing materials can be operated at room temperature with good performance, increasing its reliability for future industrial applications. Nevertheless, the relatively low response and long response/recovery time are the main drawbacks of these promising devices. Therefore, we proposed the approach to successfully increase the surface area of TMDCs by a one-step synthesis from WO3 into three-dimensional (3D) WS2 nanowalls through a rapid heating and rapid cooling process. Moreover, the combination of CdS/ZnS or CdSe/ZnS core/shell quantum dots (QDs) with different emission wavelengths and WS2 nanowalls will further improve the performance of WS2-based photodetector devices, including 3.5~4.7 times photocurrent enhancement and shorter response time. The remarkable results of the QD-WS2 hybrid devices to the high non-radiative energy transfer (NRET) efficiency between QDs and our nanostructured material are caused by the spectral overlap between the emission of QDs as the donors and the absorption of WS2 as the acceptors. Additionally, the outstanding NO2 gas-sensing properties of QDs/WS2 devices were demonstrated with a remarkably low detection limit down to 50 ppb with a fast response time of 26.8 s, contributed by tremendous local p-n junctions generated from p-type WS2 nanowalls and n-type CdSe-ZnS QDs in this hybrid system.Our strategies to combine 0D nanoparticles or quantum dots and 2D TMDC materials can significantly enhance the optical sensing and gas molecule sensing properties compared to pristine TMDC-based devices, resulting from the efficient charge or energy transfer between the multi-dimension material system and the creation of local p-n junctions. Moreover, the scalability of these hybrid nanostructures allows our devices to exhibit much more possibilities in advanced multifunctional applications.

(Keynote, Digital Presentation) First-Principles Study of Optical and Electronic Properties of Carbon Quantum Dots

We study the optical and electronic properties of carbon-based quantum dots using first-principles calculations. Based on time-dependent density functional theory we calculated absorption and emission of carbon quantum dots, we focus on the influence of surface (edge) functional groups. We can show that nitrogen groups on the carbon edges are decisive for the emission properties of small carbon quantum dots and could give rise to charge-carrier multiplication which has been suggested by recent experiments. Moreover, we explain the stability, with regard to the absorption in the optical range, of carbon quantum dots under ambient conditions. Here, we demonstrate that surface oxidation does only influence the absorption in the visible light range but does give rise to variation in the UV absorption.

Portable Plasmonic Paper-Based Biosensor for Simple and Rapid Indirect Detection of CEACAM5 Biomarker via Metal-Enhanced Fluorescence.

Rapid, simple, and sensitive analysis of relevant proteins is crucial in many research areas, such as clinical diagnosis and biomarker detection. In particular, clinical data on cancer biomarkers show great promise in forming reliable predictions for early cancer diagnostics, although the current analytical systems are difficult to implement in regions of limited recourses. Paper-based biosensors, in particular, have recently received great interest because they meet the criteria for point-of-care (PoC) devices; the main drawbacks with these devices are the low sensitivity and efficiency in performing quantitative measurements. In this work, we design a low-cost paper-based nanosensor through plasmonic calligraphy by directly drawing individual plasmonic lines on filter paper using a ballpoint pen filled with gold nanorods (AuNR) as the colloidal ink. The plasmonic arrays were further successively coated with negatively and positively charged polyelectrolyte layers employed as dielectric spacers to promote the enhancement of the emission of carboxyl-functionalized quantum dots (QD)—previously conjugated with specific antibodies—for indirect detection of the carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5). The efficiency, sensitivity, as well as the specificity of our portable nanosensor were validated by recording the luminescence of the QD@Ab complex when different concentrations of CEACAM5 were added dropwise onto the calligraphed plasmonic arrays.

(Digital Presentation) Ultraviolet CMOS Image-Sensor Embedded with Blue-Light Emitting Quantum-Dots for Analysing Air Environment Analysis

Air pollution contains sulfur dioxide (SO2) of 31.1%, nitrogen dioxide (NO2) of 27.2%, carbon oxide (COx) of 16.8%, and mineral particles of 6.3% according to the ministry of environment, Korea. Since air pollution has been harmfully affecting the health of people, the importance of controlling gas concentration and air pollution have been increased greatly and socially. To measure those gases the conventional gas detectors used by ultraviolet (UV) absorption method cannot display the image for total distribution of the gas and use public in daily life. In addition, the gas detectors used mainly at coal-fired power plant are installed in the chimney and a length of detecting probe in a detector is about 1 to 2 meters, which analyze quantitatively the gas passing through the hole with a diameter of 5-10 cm. Furthermore, since the conventional gas detectors measure only a small amount of gas coming out from chimney and their accuracies are not precise, thus, the more precise method is required for measuring the emitted gas quantitatively. In this study, therefore, we propose ultraviolet CMOS image sensor (UV-CIS) which can detect NO2 and SO2 gases quantitatively to enhance the sensitivity in detecting such gases. In particular, we investigated the characteristics of UV-CIS. We fabricated the UV-CIS embedded with blue-light emitting QD films. The structure of the UV-CIS consists of blue QDs film and blue color filter placed on conventional Si-CIS. The fabricated UV-CIS demonstrated much higher sensitivity in detecting both NO2 and SO2 gases at whole range of concentrations than conventional CIS. In particular, the sensitivity of the UV-CIS increased 1.9 times higher in detecting NO2 and 9.4 times higher in detecting SO2 than conventional CIS, respectively. It was conformed that the QD film converted UV into visible light through energy-down-conversion mechanism, which led to enhancing a sensitivity to UV light in CIS. Finally, we present energy-down-conversion characteristics of QDs synthesized, UV absorption characteristics of NO2 and SO2 gases, and the mechanism on sensing UV-light of UV-CIS to analyze an air environment.

Quantum Dots‐Functionalized Encryption Camera for Text Image Security Protection

With the wide utilization of mobile devices with a camera as online communication tools, there is a great need to develop image encryption technology for protecting confidential and sensitive information. Herein, quantum dots‐functionalized encryption (QDE) camera is proposed by integrating the fluorescence emission of quantum dots (QDs) with charge coupled device or complementary metal oxide semiconductor detector arrays during the imaging process. The variation of the photoluminescence emission from QDs controlled by UV365 nm illumination provides a convenient way to scramble the spatial distribution of RGB values in the captured image, which expands the information entropy of the captured image to realize in situ image encryption. The encrypted text images can be decrypted by a convolutional neural network‐based algorithm, resulting in high‐quality decrypted images with peak signal‐to‐noise ratio up to 45 dB. Compared with the previous reported image encryption techniques of chaotic cryptosystem, fluorescent material‐based encryption, and optical encryption, the proposed QDE camera shows advantages of high execution speed and easy miniaturization. It provides a promising in situ image encryption technique to guarantee information security in digitization process.

Bifunctional ratiometric fluorescent probe for sensing anthrax spore biomarker and tetracycline at different excitation channels

Multifunctional fluorescent probes have received increasing attention for the sake of atom economy and high-density integration. Herein, CdTe quantum dots (QDs) modified with Eu3+ were synthesized as the bifunctional ratiometric fluorescent probe for sensing two hazardous substances tetracycline (TC) and anthrax spore biomarker 2,6-dipicolinic acid (DPA) at different excitation channels, based on the discrepant excitation wavelengths of Eu3+ and the fluorescence quenching of CdTe QDs after interaction with them. Both DPA and TC enhanced the red emission of Eu3+ via antenna effect but caused the green emission of CdTe QDs to quench. Interestingly, the excitation wavelengths of Eu3+ after coordinating with DPA and TC were 275 and 386 nm, respectively. On this basis, CdTe QDs-Eu3+ achieved the bifunctional ratiometric detection of DPA (λex = 275 nm) and TC (λex = 386 nm) with different excitation channels. Both DPA and TC were selectively detected by CdTe QDs-Eu3+ with rapid response (DPA-1 min, TC-1 min) and high sensitivity (DPA-LOD 0.3 μM, TC-LOD 2.2 nM). CdTe QDs-Eu3+ were applied to analyzing DPA and TC in food, biological and environmental samples. Satisfactory spiked recoveries (80.0–119.0 %) and relative standard deviations (0.5–8.4 %) were obtained for measuring DPA and TC in these samples.