Quantum Dot Hybrid Research Articles

Printed Lithography of Graphene-Perovskite Quantum Dot Hybrid Photodetectors on Paper Substrates.

Paper is an ideal platform for creating flexible and eco-friendly electronic systems. Leveraging the synergistic integration of zero- and two-dimensional materials, it unfolds a broad spectrum of applications within the realm of the Internet of Things (IoT), spanning from wearable electronics to smart packaging solutions. However, for paper without a polymer coating, the rough and porous nature presents significant challenges as a substrate for electronics, and the absence of well-established fabrication methods further hinders its application in wearable electronics. In this study, we present photodetectors (PDs) on a paper substrate composed of graphene and CsPbBr3 perovskite quantum dots (PQDs). Hybrid structures that combine PQDs with graphene offer a promising approach for PDs. These structures benefit from robust quantum confinement in PQDs alongside improved light interaction, tunable spectra, high absorption coefficients, and an enhanced photoconductive gain mechanism in graphene, all at ambient conditions. We use a microplotter for the lithographic printing of graphene, silver electrodes, and PQDs, to fabricate PDs on paper. These PDs have an external responsivity of ∼82,000 AW-1 at 520 nm for an operating voltage ⩽1 V. The external responsivity is 3 orders of magnitude higher than state-of-the-art paper-based PDs. Under bending at L0/L = 1.15 (L0 is the arc length and L is the chord length) and after 600 bending cycles, the external responsivity is maintained up to 80%. Thus, the combination of zero- and two-dimensional materials via microplotting on a paper substrate shows promise for wearable and flexible applications.

Ultra-dispersive resonator readout of a quantum-dot qubit using longitudinal coupling

We perform readout of a quantum-dot hybrid qubit coupled to a superconducting resonator through a parametric, longitudinal interaction mechanism. Our experiments are performed with the qubit and resonator frequencies detuned by ~10 GHz, demonstrating that longitudinal coupling can facilitate semiconductor qubit operation in the ‘ultra-dispersive’ regime of circuit quantum electrodynamics.

Gold-Graphene Quantum Dot Hybrid Nanoparticle for Smart Diagnostics of Prostate Cancer.

Prostate cancer is one of the most prevalent cancers afflicting men worldwide, often detected at advanced stages, leading to increased mortality rates. Addressing this challenge, we present an innovative approach employing electrochemical biosensing for early-stage prostate cancer detection. This study used Indium-Tin Oxide (ITO) as a substrate and a deposited gold-graphene quantum dot (Au-GQD) nanohybrid to establish electrochemical sensing platforms for DNA-hybridization assays. A capturing DNA probe, PCA3, was covalently immobilized on the surface of the Au-GQDs and deposited electrochemically onto the ITO electrode surface. The Au-GQDs enabled the capturing of the target PCA3 biomarker probe. The sensor achieved a limit of detection (LoD) of up to 211 fM and presented a linear detection range spanning 1 µM to 100 fM. A rapid 5-min response time was also achieved. The tested shelf life of the pre-immobilized sensor was approximately 19 ± 1 days, with pronounced selectivity for its intended target amidst various interferants. The sensing device has the potential to revolutionize prostate cancer management by facilitating early-stage detection and screening with enhanced treatment efficacy.

High volumetric-energy-density flexible supercapacitors based on PEDOT:PSS incorporated with carbon quantum dots hybrid electrodes

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a highly successful conductive polymer utilized as an electrode material in energy storage units for portable and wearable electronic devices. Nevertheless, employing PEDOT:PSS in supercapacitors (SC) in its pristine state presents challenges due to its suboptimal electrochemical performance and operational instability. To surmount these limitations, PEDOT:PSS has been integrated with carbon-based materials to form flexible electrodes, which exhibit physical and chemical stability during SC operation. We developed a streamlined fabrication process for high-performance SC electrodes composed of PEDOT:PSS and carbon quantum dots (CQDs). The CQDs were synthesized under microwave irradiation, yielding green- and red-light emissions. Through optimizing the ratios of CQDs to PEDOT:PSS, the SC electrodes were prepared using a spray-coating technique, marking a significant improvement in device performance with a high volumetric capacitance (104.10 F cm−3), impressive energy density (19.68 Wh cm−3), and excellent cyclic stability, retaining ∼85% of its original volumetric capacitance after 15,000 repeated GCD cycles. Moreover, the SCs, when utilized as a flexible substrate, demonstrated the ability to maintain up to ∼85% of their electrochemical performance even after 3,000 bending cycles (at a bending angle of 60°). These attributes render this hybrid composite an ideal candidate for a lightweight smart energy storage component in portable and wearable electronic technologies.

Engineered self-assembled protein nanosheets for in situ biosynthesis of peptide anchored protein-semiconductor hybrids for efficient hydrogen production

Catalytic hydrogen production using solar energy is of great significance in addressing the global energy crisis. Herein, an efficient artificial photocatalytic hydrogen production system based on hierarchical protein self-assembly is designed and developed by in situ biosynthesis of peptide-anchored protein-semiconductor hybrids. The self-grown protein-CdS quantum dot hybrids stabilize and array orderly by the predesigned bioengineered proteins assembled into monolayer nanosheets, perfectly mimicking both the structure and function of the natural photosynthetic system. By mild deposition of Pt nanoparticles, the photocatalytic hydrogen production performance of the system is further enhanced to 69100 μmolh−1 (Cd2+) g −1, 80 times the catalytic activity of free CdS. Remarkably, the protein 2D network effectively enhances the water solubility, dispersibility, and solution stability of the inorganic catalytic centers, affording efficient photocatalytic hydrogen evolution. The system maintains 91.2 % catalytic efficiency after 30 days. Furthermore, its hydrogen production rate can be artificially regulated between 69100 and 52100 μmolh−1 (per g Cd2+) by the assembly-disassembly process of the protein templates. Thus, our work showcases the importance of the protein template and its assembly in maintaining the structural stability and high catalytic performance of the photocatalytic system and provides promising ideas for the simulation of natural photosynthetic systems.

Investigation on luminescence photoswitching stability in diarylethene-perovskite quantum dot hybrids.

Perovskite quantum dots (pQDs) have gathered a lot of attention because of their outstanding optoelectronic properties. Photoswitchable pQDs have the potential for application in single particle optical memories and bio-imaging. Hybrids of photochromic diarylethenes (DAE) and pQDs show a luminescence photoswitching property, however, the cycle stability in such systems is low because of photoinduced electron transfer (PET) from pQDs to DAE. In this study, various hybrids of DAEs and pQDs with different spacer lengths between the pQD donors and DAE acceptors were synthesized and their stability towards multiple cycles of luminescence photoswitching was evaluated. It was found that the electron transfer pathway can be blocked and very stable switchable hybrids can be produced when the distance between the donors and acceptors was long enough. Furthermore, the effect of softness of the basic ligands and the synthesis method of the pQDs on the cycle stability of the hybrids were investigated. The findings of this study suggest that the photoswitching stability can be improved in hybrid systems by proper molecular design of the photochromic molecule.

Enhancing photocatalytic hydrogen production from engineered Escherichia coli-biohybrid system via intracellular electron redirection

The development of biotic-abiotic photosynthetic systems is becoming one of the most promising strategies towards the thirsty demand for sustainable energy production. However, considerable efforts are still required to further optimize the design and avoid the utilization of high-value substances while achieving highly efficient hydrogen production. Here we show a way to construct an Escherichia coli (E. coli)-quantum dots hybrid system by expressing ferredoxin (Fd), Fd-NAD(P)+ reductase (FNR), and [FeFe]-hydrogenase ([FeFe]H2ase) as a potential biocatalyst. We reveal that electrons originating from the quantum dots could be redirected through the newly established electron transport chain NADH/NAD+-FNR-Fd to [FeFe]H2ase, which contributes a key mechanism to boost the highest H2 production activity (3149.5 μmol gdcw−1h−1) by only using glycerol as the carbon source. Our work sheds light on the advantages of an intracellular biological hybrid system by combining the photocatalytic capacity with the optimized metabolic power to produce biofuels.

Air-stable and UV-NIR broadband photodetectors utilizing graphene and core/shell quantum dots hybrid heterostructure

Photodetectors based on PbSe quantum dots (QDs) are commonly used for light detection in the near-infrared (NIR) region. Nevertheless, the performance of photodetectors based on PbSe QDs is constrained by ineffective carrier transfer and poor photo and thermal stabilities. Herein, a promising strategy that harnesses PbSe/PbS core/shell QDs structures is developed and demonstrated to enhance the long-term stability of photodetectors, further combining with graphene to form hybrid heterojunctions that effectively promote carrier transfer. As a result, the devices exhibit a broad photoresponse to the incident light at range of 365–1250 nm, and also possess a high photosensitivity of 1.5 × 104 A/W and a high detectivity of 4.0 × 1013 Jones. Moreover, the lifetime of graphene-PbSe/PbS core/shell QDs hybrid photodetector was 9 times greater than that of uncoated QDs devices. The enormous boost might be attributed to the passivation and protection provided by the core–shell structure, and graphene’s efficient extraction of charge carriers.

Third- and fifth-order nonlinearities in quantum dot hybrid systems: Influence of graphene and metal nanoparticles

This work examines the third-order and fifth-order nonlinear susceptibilities in a hybrid system including a semiconductor quantum dot, metallic nanoshell, and graphene nanodisk. The research uses the density matrix method to examine the dipole–dipole interaction that occurs due to the applied field. It assumes that there is an increase in the strength of a continuous-wave electromagnetic field inside the quantum dot. The inclusion of the graphene nanodisk greatly amplifies the nonlinear optical reaction of the quantum dot in this combined system, which is governed by the dipole–dipole interaction. The findings indicate a notable disparity in the nonlinear optical reaction of the semiconductor quantum dot when the parameters are modified. The possible applications of this concept include optical sensors, photonic devices, quantum computing, medical imaging, energy harvesting, and high-density data storage. Additionally, it has the potential to progress terahertz technology and simplify the development of new materials with customized optical properties. The substantial rise in nonlinearities inside the hybrid system presents prospects for advancements in diverse technological and scientific domains.

Bipolar resistive switching behavior of PVA/g-C3N4 quantum dots hybrid thin films

Graphite-phase carbon nitride quantum dots (g-C3N4 QDs) have garnered widespread attention and considerable research interest as active media for resistive random-access memory (RRAM) devices owing to their exceptional physical properties. In this study, g-C3N4 QDs were synthesized via ultrasonic-assisted liquid-phase exfoliation. Subsequently, the obtained g-C3N4 QDs with uniform size were embedded into polyvinyl alcohol (PVA) for preparing PVA/g-C3N4 QDs hybrid, and the RRAM devices with Al/g-C3N4 QDs-PVA/ITO/PET structure were fabricated. The obtained memory devices exhibit bipolar resistive switching (BRS) behavior and are primarily influenced by the space charge limited conduction (SCLC) mechanism. The data retention time exceeds 104 s at a read voltage of 0.1 V, accompanied by an impressively low set voltage. In addition, the device exhibits a surprising temperature dependence of the resistive switching performance at different temperatures. The aforementioned properties demonstrate the significant potential of g-C3N4 QDs in RRAM for data storage applications.

(Invited) Reshaping Light with Hybrid Quantum Dot: Molecule Systems

Photon upconversion is an energy conversion process wherein a material absorbs two or more low-energy photons and uses their energy to generate high-energy photons. Upconversion systems that convert near-infrared light into the visible range can address current challenges in solar energy capture and near-infrared sensor design while materials that operate at higher energy, producing UV photons from visible light, can enable applications in photocatalysis and light-based 3D printing. Due to their high extinction coefficients and size-tunable optical properties, quantum dots have emerged as ideal photosensitizers for photon upconversion systems. In these systems, light absorbed by a quantum dot is passed to a molecule at its surface, placing the molecule into a spin-triplet state. Upconversion is achieved when two molecules in their triplet state encounter one another and undergo triplet fusion, a process that deexcites one molecule and promotes the other to a high-energy, emissive spin-singlet state. In this presentation, I will present spectroscopic measurements and electronic structure calculations that identify energy transfer rates and key intermediates involved in two quantum dot systems that respectively demonstrate red-to-blue and blue-to-UV photon upconversion. In the first system, which consists of silicon quantum dots functionalized with anthracene ligands, we find that by controlling the chemical structure of molecular tethers that covalently link anthracene to silicon, we can produce strongly coupled states wherein excited charge carriers are shared between silicon and anthracene. By controlling the energy of these states, we can optimize the system’s performance, achieving an upconversion quantum yield of 17.2%. In the second system, we use CsPbBr3 perovskite quantum dots to drive triplet energy transfer to naphthalene ligands. This energy transfer process is found to be highly sensitive to the structure of the chemical linker that binds naphthalene to CsPbBr3, which we attribute to modulation of the degree of wavefunction overlap between the states of the quantum dot energy donor and naphthalene energy acceptor.

Investigating the optical and magnetic properties of engineered multifunctional graphene oxide and potential application in medical physics and nonlinear optics‏

Herein, the synthesis of multifunctional engineered GOs with the structure of GO@Fe3O4-ligands-CdTe quantum dots (QDs) by an environment-friendly aqueous method was reported. l-cystein (Cys), 3-trimethoxysilyl-propanethiol (TMSP), and glutathione (GSH) were selected as ligands. The as-prepared GO@Fe3O4-ligands-CdTe QDs hybrid nanostructures were characterized by different methods. The findings indicate that the nanocomposites of GO@Fe3O4–ligands–CdTe QDs demonstrate superparamagnetic properties at room temperature. The saturation magnetization values for GO@Fe3O4, GO@Fe3O4-Cys-CdTe, GO@Fe3O4-GSH-CdTe, and GO@Fe3O4-TMSP-CdTe, are 25, 14, 16, and 2 emu g−1, respectively. These nanocomposites show stable and strong luminescence at 580-600 nm. The magnetic nanostructures also reveal the absorption wavelength at 300-490 nm. Using TMSP ligand as a bridge between QDs and magnetic GOs, the luminescence of the nanostructure has not decreased much compared to CdTe QDs. The use of Cys ligand preserves the saturation magnetism of the nanocomposite more than magnetic GO, and the dispersed nanostructure is stable in water. Furthermore, the transverse and longitudinal optical (TO and LO) phonon modes of prepared GO@Fe3O4–ligands–CdTe QDs were obtained by Kramers-Kronig (KK) relations based on fourier-transform infrared (FTIR) spectroscopy. The Z-scan results show that the type of used ligand has a great effect on the nonlinear optical (NLO) properties of the final product. The largest NLO parameters are related to GO@Fe3O4- TMSP -CdTe QDs, and the values of nonlinear absorption coefficient and nonlinear refractive index were obtained as 2.17×10−3(cm/W) and10.27×10−8(cm2/W), respectively. As a result, GO@Fe3O4–ligands–CdTe QDs nanostructures can be considered as promising multifunctional nanostructures for various biomedical applications and NLO devices.

High Color Conversion Efficiency Realized in Graphene‐Connected Nanorod Micro‐LEDs Using Hybrid Ag Nanoparticles and Quantum Dots

AbstractIn this paper, a uniform nanorod (NR) array is etched onto the surface of Micro‐Light‐Emitting‐Diodes (µLEDs) and mix Ag nanoparticles (NPs) with QDs to fill the gaps between the nanorods. Simultaneously, the study utilizes graphene to connect individual nanorods and enhance current spreading. The nanorod array's structure significantly reduces the distance between the QDs and the quantum well (QW), reducing energy loss from the excitation light source through a non‐radiative energy transfer (NRET) mechanism. Additionally, the Ag NPs function as localized surface plasmons (LSPs), further enhancing the CCE of QDs via the absorption resonance. In this study, the effects of two types of Ag NPs are compared with different absorption resonance peaks on device performance. The results demonstrate that Ag NPs with absorption resonance peaks matching the emission wavelength of QDs play a more crucial role in the system. This configuration achieves a CCE of 77.78% for µLEDs with nanorod arrays, operating at a current of 10 mA. Compared to the conventional µLED structure with QDs only on the surface, the proposed method improves the CCE of µLEDs by an impressive 86.5%. This outcome underscores the significant contribution of the NR structure and LSPs in enhancing the CCE of QD‐µLEDs.

Correlation between two distant quasiparticles in separate superconducting islands mediated by a single spin

Controlled coupling between distant particles is a key requirement for the implementation of quantum information technologies. A promising platform are hybrid systems of semiconducting quantum dots coupled to superconducting islands, where the tunability of the dots is combined with the macroscopic coherence of the islands to produce states with non-local correlations, e.g. in Cooper pair splitters. Electrons in hybrid quantum dots are typically not amenable to long-distance spin alignment as they tend to be screened into a localized singlet state by bound superconducting quasiparticles. However, two quasiparticles coming from different superconductors can overscreen the quantum dot into a doublet state, leading to ferromagnetic correlations between the superconducting islands. We present experimental evidence of a stabilized overscreened state, implying correlated quasiparticles over a micrometer distance. We propose alternating chains of quantum dots and superconducting islands as a novel platform for controllable large-scale spin coupling.

Carbon-silicon based hybrid quantum dot short wave infrared photodetector

Recently infrared photodetectors based on low-dimensional semiconductors have developed rapidly. However, due to its poor light absorption and incompatibility with traditional silicon-based readout circuit processes, the sensitivity and integration of such photodetectors are limited. In this work, we proposes a 64 × 64 quantum dot short-wavelength infrared (SWIR) photodetector composed of carbon nanotube thin film transistor (CNT TFT) and silicon-based ROIC. CNT TFT's gate is constructed by PbS colloidal quantum dots (PbS CQDs) which improve the absorption rate of infrared light. The generated photovoltage is amplified and converted in situ by CNT TFT. Notably, under infrared radiation of 1300 nm, the noise equivalent current reach up to 1.25*10−13A/Hz1/2. At a drain-source bias (Vds)= -0.1 V. The device exhibits detectivity of 5.6*1013 Jones and a fast response of 0.57 ms. The silicon-based ROIC is implemented by CMOS 0.18um process, with a power supply voltage of 1.8 V. It mainly includes a programmable integrator, a sampling and holding circuit, and a 10bit/2.5 MHz successive approximation analog-to-digital converter (SAR ADC). The programmable integrator has four levels of integral gain to meet the application requirements of different infrared light intensities. The experiment results show that the imaging function of the overall photodetector is correct, laying the foundation for the development of carbon-silicon based heterojunction integrated photodetector in the future.

Sensitive electrochemical sensing of imidacloprid based on mulberry-like gold-graphene quantum dots hybird as electrode material

The rapid synthesis of gold nanocrystal with high catalytic activity is still a great challenge to improve the analytical performance of electrochemical sensors. In this paper, gold-arginine-threonine functionalized graphene quantum dot hybrid (Au-Arg-Thr-GQD) was synthesized by a simple and fast one-step method using Arg-Thr-GQD as reductant, stabilizer and crosslinker. The Au-Arg-Thr-GQD offers mulberry-shaped structure by the interconnection and self-assembly of Arg-Thr-GQD and small-sized Au nanocrystals. The unique structure significantly improves the catalytic activity of hybrid. Au-Arg-Thr-GQD was used as a sensing material for electrochemical analysis of imidacloprid. Under the optimal conditions, the differential pulse voltammetry peak current linearly increased with the increasing of imidacloprid concentration in the range of 0.1–20 μM with the detection limit of 0.011 μM. The proposed imidacloprid sensor shows high selectivity, good stability and reproducibility, and has been successfully applied to the determination of imidacloprid in cabbage and cucumber samples.

Out-of-equilibrium voltage and thermal bias response of a quantum dot hybrid system coupled to topological superconductor

We investigate theoretically the out-of-equilibrium transport properties of a single-level quantum dot coupled to a normal metal electrode and attached to a topological superconductor. Both voltage and thermal bias responses of the system in the nonequilibrium regime are studied. To obtain transport characteristics we used the nonequilibrium Green’s function approach. Particularly, we calculated the current and the corresponding differential conductance in two distinct cases. In the former situation, the charge current is induced by applying a bias voltage, whereas in the latter case it is generated by setting a temperature difference between the leads with no bias voltage. Moreover, strong diode effect in thermally generated current is found and non-equilibrium thermopower is analyzed.

Tribological properties of graphene quantum dot hybrid polyethylene glycol lubricated molybdenum disulfide films

Herein, molybdenum disulfide (MoS2) films were obtained by magnetron sputtering, and graphene quantum dots (GQDs) prepared by the hydrothermal method were used as additives for polyethylene glycol (PEG) lubricants to investigate the tribological mechanisms under solid-liquid composite lubrication. The friction coefficient of GQDs hybridized PEG lubricated MoS2 solid-liquid composite films was reduced by 69.23%, and the wear rate was reduced by 79.31% as compared to solid lubrication (MoS2 film). This solid-liquid complex lubrication occurs mainly as abrasive wear. GQDs form a uniform and dense amorphous carbon film on the corresponding balls to protect the wear between the friction pair. This work demonstrates the great potential of zero-dimensional and two-dimensional materials for solid-liquid composite lubrication.

Carbon-TiO2 Hybrid Quantum Dots for Photocatalytic Inactivation of Gram-Positive and Gram-Negative Bacteria.

Carbon-semiconductor hybrid quantum dots are classical carbon dots with core carbon nanoparticles doped with a selected nanoscale semiconductor. Specifically, on those with the nanoscale TiO2 doping, denoted as CTiO2-Dots, their synthesis and thorough characterization were reported previously. In this work, the CTiO2-Dots were evaluated for their visible light-activated antibacterial function, with the results showing the effective killing of not only Gram-positive but also the generally more resistant Gram-negative bacteria. The hybrid dots are clearly more potent antibacterial agents than their neat carbon dot counterparts. Mechanistically, the higher antibacterial performance of the CTiO2-Dots is attributed to their superior photoexcited state properties, which are reflected by the observed much brighter fluorescence emissions. Also considered and discussed is the possibility of additional contributions to the antibacterial activities due to the photosensitization of the nanoscale TiO2 by its doped core carbon nanoparticles.

Au/SnS2 Hybrid Quantum Dots for Surface-Enhanced Raman Scattering-Based Monitoring and Photoreduction of Hg (II) Ions

Au/SnS₂ Hybrid Quantum Dots for Surface-Enhanced Raman Scattering-Based Monitoring and Photoreduction of Hg (II) Ions