Stability Of Quantum Dots Research Articles

Ambipolar quantum dots in undoped silicon fin field-effect transistors

We integrate ambipolar quantum dots in silicon fin field-effect transistors using exclusively standard complementary metal-oxide-semiconductor fabrication techniques. We realize ambipolarity by replacing conventional highly doped source and drain electrodes by a metallic nickel silicide with the Fermi level close to the silicon mid-gap position. Such devices operate in a dual mode, as either a classical field-effect or single-electron transistor. We implement a classical logic NOT gate at low temperature by tuning two interconnected transistors into opposite polarities. In the quantum regime, we demonstrate stable quantum dot operation in the few charge carrier Coulomb blockade regime for both electrons and holes.

Halide-, Hybrid-, and Perovskite-Functionalized Light Absorbing Quantum Materials of p-i-n Heterojunction Solar Cells.

The p-i-n quantum dot (QD) solar cells were fabricated through the single-step deposition of both of its p-type and light absorbing quantum layers. The hole transport and light absorbing layers of these devices were made by the p- and n-type PbS QDs, which were functionalized with mercaptopropionic acid and different halide, hybrid, and perovskite ligands, respectively. Fabrication of such p-i-n devices by the single-step deposition of pre-exchanged colloidal QDs had not been fully investigated so far because of the low progression of ligand exchange processes, weak colloidal stability of pre-exchanged QDs in desired solvents, and remaining of the ligand exchange products along with particles. However, we showed that the type of ligand complexes, amino acid products of ligand exchange, and protic solvents are highly effective for increasing the ligand exchange progression and preparation of high colloidal stability QDs with superior photoluminescence properties. As well, the surface chemistry investigations by the means of Fourier transform infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction, inductively coupled plasma optical emission spectrometry, carbon-hydrogen-nitrogen-sulfur elemental analysis, zeta potential, and high-resolution transmission electron microscopy were led to the presentation of new concepts about the theoretical and experimental ligand weight percentages, the mechanisms of solution-phase ligand exchange processes, and formation of ligands adlayer on the (111) facets of QDs. The pre-exchanged colloidal QDs showed very good desirability for the single-step deposition of dense, defects-free, and smooth QD layers. Regarding that, the p-i-n solar cells were successfully fabricated by the single-step deposition of both of the QD layers. Especially, the highest power conversion efficiency value of 6.40% was recorded for the devices in which the light absorbing layer was prepared by the composite-like QD-perovskite structures.

Extracellular biosynthesis of biocompatible cadmium sulfide quantum dots using Trametes versicolor

Quantum dots are important fluorescent semiconductor nano-crystals with distinguished electrical and optical properties and have gained great interest in many fields. The chemical and physical synthetic methods are usually not favorable for biological application due to high energy-consumption procedure and residual toxic chemicals. The development of novel “green” routes to prepare bio-compatible cadmium sulfide quantum dots constitutes a promising substituted approach. We used the white rot fungus Trametes versicolor for the biosynthesis of cadmium sulfide quantum dots taking account of the adsorption property of this fungus. Multiple physical characterizations involving scanning electron microscope (SEM), ultraviolet-visible (UV–vis) and photoluminescence (PL) spectroscopy, fourier transform infrared spectroscopy (FTIR), thermo-gravimetric (TG), transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed surface, optical and thermal characteristics, crystalline nature, size and shape distributions of the nanoparticles. This study provided a suitable and efficient approach to synthesize stable biocompatible cadmium sulfide quantum dots using the fungus Trametes versicolor with great potentials in the biological and biomedical researches.

White Quantum‐Dot LEDs: Efficient and Color Stable White Quantum‐Dot Light‐Emitting Diodes with External Quantum Efficiency Over 23% (Advanced Optical Materials 16/2018)

Highly efficient and color stable white quantum dot light-emitting diodes have been demonstrated by Shuming Chen and co-workers (article number 1800354) by using a red/green/blue three-unit tandem or a blue/green:red two-unit tandem structure. The demonstrated tandem devices exhibit a pure white emission and an impressively high external quantum efficiency of 23%.

(Invited) Epitaxy and Applications of Group-IV Semiconductors in Quantum Computing

The first quantum revolution provided a microscopic understanding of nature and underpinned the development of transistors, originally made in germanium. The following assembly of silicon transistors into integrated circuits triggered the digital age, which completely changed our daily life. We are now in the midst of the second quantum revolution, in which quantum matter is engineered to develop disruptive technologies beyond the reach of classical understanding. Quantum computing is considered by many the man on the moon goal of such second quantum revolution. How will we get there? In this talk I will discuss, from a materials perspective, how we are turning everyday silicon into the quantum computing wonder material by using quantum dots defined electrostatically in SiGe heterostructures. Group-IV semiconductors Si and Ge offer several advantages for the realization of spin quantum bits. Si and Ge can be isotopically purified into a nuclear spin free materials, which allows long spin coherence time. A quantum dot defined by metallic gates in a strained Si/SiGe heterostructure can trap a single electron, such that the electron spin can be operated as a quantum bit, the elementary unit of quantum computation. Quantum dots in Si/SiGe heterostructure are promising because bear similarities from a materials and integration perspective to the transistors used in advanced semiconductor manufacturing. Advanced quantum control in Si qubits allows to run quantum algorithms on two qubit processors. Strong spin-photon coupling has been achieved in Si, a first step towards realizing large networks of quantum dot based spin qubit registers.[1] Additionally, SiGe heterostructures allows us to explore high mobility holes in strained Ge as a complementary option for fast quantum hardware due to the different band structure properties of Ge compared to Si. Recently, gate-controlled stable quantum dots were demonstrated in planar Ge, a first step towards Ge hole qubits.[2] However, to deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. In this talk we will focus on carrier mobility and energetic valley splittings in SiGe heterostructures, which are two key electrical metrics of substrate quality relevant for qubits. To ensure rapid progress in quantum wells development we have implemented fast feedback loops from materials growth, to innovative heterostructure field effect transistor fabrication, and low temperature characterization. In this direction we show progress in developing a cryogenic platform for high-throughput magnetotransport measurements. [1] N. Samkharadze, G. Zheng, N. Kalhor, D. Brousse, A. Sammak, U. C. Mendes, A. Blais, G. Scappucci, and L. M. K. Vandersypen, Science , eaar4054 (2018). [2] N. W. Hendrickx, D.P. Franke, A. Sammak, M. Kouwenhoven, D. Sabbagh, L. Yeoh, R. Li, M. L. V. Tagliaferri, M. Virgilio, G. Capellini, G. Scappucci, M. Veldhorst, arXiv:1801.08869 (2018)

Colour- and structure-stable CsPbBr3-CsPb2Br5 compounded quantum dots with tuneable blue and green light emission

Even though all-inorganic lead halide perovskite (CsPbX3; X = Cl, Br, I) quantum dots (QDs) with great optoelectronic properties such as high fluorescence quantum yield, facile colour tunability, and high colour purity have been under the spotlight in recent years, their poor stability makes their application in LEDs difficult. In comparison to CsPbBr3 QDs that display green emission, CsPbCl3 QDs with blue light emission contain more defects in the material and exhibit lower fluorescence quantum yield and device service time, which is the bottleneck in realizing blue, green, and red three-base coloured perovskite QD-based LEDs. It is therefore a pressing issue to develop other techniques instead of anion exchange to adjust the light emission of CsPbX3 and simultaneously enhance the stability of the nanocrystals, especially for blue emission. In this work, CsPbBr3 QDs compounded with CsPb2Br5 (CsPbBr3-CsPb2Br5 QDs) with stable blue and green emissions are obtained using improved one-step solution-phase method. CsPb2Br5 can enhance the luminescent colour and structural stability of CsPbBr3 QDs. CsPbBr3-CsPb2Br5 QDs showed greater stability than pure CsPbBr3 QDs in various environments. Moreover, CsPbBr3-CsPb2Br5 QDs are smaller than CsPbBr3 QDs synthesized at the same temperature, which results in blue-shift of the photoluminescence spectra. Owing to the strong stability, their photoluminescence emission peak can be simply and reliably tuned continuously between 480 nm and 520 nm through the reaction temperature.

Towards the fluorescence retention and colloidal stability of InP quantum dots through surface treatment with zirconium propoxide

ABSTRACTThrough the synthetic development of sophisticated core/shell heterostructures, the fluorescent properties of quantum dots (QDs) have been steadily improved to a level that can ultimately meet the industrial demands, but their reliability is still insufficient, particularly showing low fluorescence stability against degradable conditions. As one solution to this issue, an additional physical barrier typically with an oxide phase has been introduced to protect the QD surface from the environment. In this work, a strategy for improving the stability of QDs involving the passivation of their surfaces with zirconium propoxide (Zr(PrO)4) is suggested. Multi-shelled green QDs of InP/ZnSeS/ZnS were first synthesized, and then their surfaces were in-situ-treated with Zr(PrO)4. To confirm the presence of Zr(PrO)4-derived species on the QD surfaces, chemical analyses of the Zr(PrO)4-treated QDs were performed through Fourier transform infrared, X-ray photoelectron, and inductively coupled plasma optical emission spectroscopic measurements. A photostability test of two comparative InP/ZnSeS/ZnS QDs – one treated without and one with Zr(PrO)4 – was performed by exposing their dispersions to ultraviolet (UV) irradiation for prolonged periods of time, up to 120 h. It was revealed that Zr(PrO)4 treatment is highly effective in improving fluorescence retention and colloidal stability.

Silica encapsulated ZnO quantum dot-phosphor nanocomposites: Sol-gel preparation and white light-emitting device application**Project supported by the National Natural Science Foundation of China (Grant Nos. 21601159, 61604132, and U1604263) and the National Science Fund for Distinguished Young Scholars of China (Grant No. 61425021).

ZnO quantum dots (QDs) as an eco-friendly and low-cost material has bright fluorescence, which makes it promising material for healthy lighting and displaying. However, the low fluorescence efficiency and poor stability of ZnO QDs impede their applications in lighting application. In this work, silica encapsulated ZnO QD-phosphors nanocomposites (ZSPN) have been prepared through a sol-gel synthesis process, where yellow-emitting ZnO QDs and blue-emitting BaMgAl10O17:Eu2+ are employed as the luminescence cores and silica as link between two luminescence materials. Tunable photoluminescence of ZSPN and the white light emission have been achieved through changing mass ratio of both of ZnO QDs and commercial phosphors. The PLQY of the ZSPN can reach 63.7% and they can maintain high luminous intensity even the ambient temperature up to 110 °C and after 35 h of UV irradiation. In addition, they can keep stable for 40 days. By coating the ZSPN phosphors onto a ultraviolet chip, WLEDs with luminous efficiency of 73.6 lm/W and the color coordinate, correlated color temperature, and color rendering index can reach (0.32, 0.34), 5580 K, and 87, respectively, indicating the bright prospect of the ZSPN phosphors used in healthy lighting.

Exceptional Catalytic Nature of Quantum Dots for Photocatalytic Hydrogen Evolution without External Cocatalysts

AbstractThe catalytic nature of semiconducting quantum dots (QDs) for photocatalytic hydrogen (H2) evolution can be thoroughly aroused, not because of coupling with external cocatalysts, but through partially covering controlled amount of ZnS shell on the surface. Specifically, CdSe QDs, with an optimal coverage of ZnS (≈46%), can produce H2 gas with a constant rate of ≈306.3 ± 21.1 µmol mg−1 h−1 during 40 h, thereby giving a turnover number of ≈(4.4 ± 0.3) × 105, which is ≈110‐fold to that of unmodified CdSe QDs under identical conditions. The performance of H2 evolution is comparable to or even better than the commonly used external cocatalysts, e.g., metal complexes, noble metals assisted photosystems. Mechanistic insights indicate that the dramatically enhanced activity and stability of bare QDs for photocatalytic H2 production are derived from (i) inhibiting exciton annihilation at trap states, (ii) preventing the photo‐oxidation of core frameworks, and (iii) retaining tunneling efficiencies of photogenerated electrons and holes to reactive sites with partial ZnS coverage.

Synthesis and characterization of Bi2S3 quantum dot-sensitized TiO2 nanorod arrays coated with ZnSe passivation layers

Stable Bi2S3 quantum dots (QDs) prepared by a modified successive ionic layer adsorption and reaction (SILAR) method were used to decorate TiO2 nanorod (TNR) arrays and enhance their photoelectrochemical (PEC) performance. In the above procedure, elemental sulfur vapor was utilized as a precursor instead of aqueous Na2S to prevent the photodecomposition of QDs, whereas the hydrolysis of the Bi precursor (Bi(NO3)3) was prevented by using 3-mercaptopropionic acid as a stabilizer, and interfacial charge recombination was inhibited by depositing ZnSe passivation layers. The prepared photoelectrodes were subjected to morphological, structural, compositional, and optical/PEC property analyses, and the ideal bandgap and high absorption coefficient of Bi2S3 QDs was shown to result in enhanced visible light absorption properties and PEC performance of QD–sensitized TNR thin films, as compared to those of bare TNR films. The deposition of ZnSe on sensitized films resulted in further PEC performance enhancement, achieving a photocurrent density of 0.11 mA/cm2 and an electron lifetime of 37.9 ms, which was attributed to the effective suppression of charge carrier recombination by ZnSe passivation layers. Thus, the facile synthesis and environmentally friendly nature of Bi2S3 QD–sensitized TNR films coated with ZnSe passivation layers make them promising components of solar energy–driven devices.

Bandgap Tunable AgInS based Quantum Dots for High Contrast Cell Imaging with Enhanced Photodynamic and Antifungal Applications

Herein, we report a facile microwave-assisted synthesis of cadmium-free water-soluble silver indium sulfide (AgInS2 or AIS) and AgInS@ZnS (or AIS@ZnS) core-shell quantum dots (QDs) using glutathione (GSH) as stabilizer. The core and core-shell nanocrystals exhibit tunable bandgap ranging of 2.3–3.1 and 2.4–3.5 eV, mean particle size of 2.5 and 3.25 nm, quantum yield of 26% and 49%, and fluorescence lifetimes of 326 and 438 ns, respectively. The core-shell QDs exhibit color-tunable emission in the visible region (500 to 600 nm), where the tunability was achieved by varying the molar ratio of Ag:In in the precursors. In vitro evaluation of antifungal activity of these water/ buffer stable QDs against the fungal pathogen, Candida albicans demonstrated that these were not toxic to the fungal cells upto a concentration of 100 µg/ml for 16 hours of incubation. Confocal imaging and spectrofluorometric studies showed enhanced fluorescence inside the microbial cells suggesting that AIS@ZnS particles had the capability to easily penetrate the cells. The increased generation of reactive oxygen species was evaluated for the core-shell QDs (photosensitizers) by using 9, 10-anthracenediyl-bis(methylene)dimalonic acid (ABMDMA) as singlet oxygen (1O2) scavenger molecule. These QDs have the potential for use as high contrast cell imaging, photodynamic and antifungal agents.

Efficiency and stability enhancement of perovskite solar cells by introducing CsPbI3 quantum dots as an interface engineering layer

Although great efforts have been devoted to enhancing the efficiency and stability of perovskite solar cells (PSCs), the performance of PSCs has been far lower than anticipated. Interface engineering is helpful for obtaining high efficiency and stability through control of the interfacial charge transfer in PSCs. This paper demonstrates that the efficiency and stability of PSCs can be enhanced by introducing stable α-CsPbI3 quantum dots (QDs) as an interface layer between the perovskite film and the hole transport material (HTM) layer. By synergistically controlling the valence band position (VBP) of the perovskite and the interface layer, an interface engineering strategy was successfully used to increase the efficiency of hole transfer from the perovskite to the HTM layer, resulting in the power conversion efficiency increasing from 15.17 to 18.56%. In addition, the enhancement of the stability of PSCs can be attributed to coating inorganic CsPbI3 QDs onto the perovskite layer, which have a high moisture stability and result in long-term stability of the PSCs in ambient air.

In Situ Crystallization Synthesis of CsPbBr3 Perovskite Quantum Dot-Embedded Glasses with Improved Stability for Solid-State Lighting and Random Upconverted Lasing.

All-inorganic cesium lead bromide CsPbBr3 perovskite quantum dots (QDs) are emerging as potential candidates for their applications in optoelectronic devices but they suffer from poor long-term stability due to their high sensitivity to UV irradiation, heat, and especially to moisture. Although great advances in improving stability of perovskite QDs have been achieved by surface modification or encapsulation in polymer and silica, they are not sufficiently refrained from external environment due to nondense structures of these protective layers. In this work, in situ nanocrystallization strategy is developed to directly grow CsPbBr3 QDs among a specially designed TeO2-based glass matrix. As a result, QD-embedded glass shows typical bright green emission assigned to exciton recombination radiation and significant improvement of photon/thermal stability and water resistance due to the effective protecting role of dense structural glass. Particularly, ∼90% of emission intensity is even remained after immersing QD-embedded glass in water up to 120 h, enabling them to find promising applications in white-light-emitting device with superior color stability and low-threshold random upconverted laser under ambient air condition.

Dependence of halide composition on the stability of highly efficient all-inorganic cesium lead halide perovskite quantum dot solar cells

All-inorganic perovskites suffer from low temperature phase instability and degradation under moisture and polar solvents. Here we have synthesized organic ligand assisted stable perovskite quantum dots (QDs) with uniform size ~10 nm. Varying the composition in CsPbBrxI3-x it was observed that CsPbBr1.5I1.5 could be an alternative solution for stable perovskite QDs. Photoluminescence (PL) decay showed comparable average lifetime useful for photovoltaic (PV) application. The photovoltaic devices made from CsPbBr1.5I1.5 showed power conversion efficiency (PCE) ~7.94% with open circuit voltage ~ 1.0 V, fill factor 0.70 and long term stability. This PCE is also the highest as compared to other PV reports for QDs with CsPbBr1.5I1.5 composition. Moreover this composition offers nearly hysteresis free perovskite device.

Highly stable and bio-compatible luminescent molybdenum disulfide quantum dots for imaging of alimentary canal in Drosophila

Investigations on inorganic luminescent nanomaterials have always gained enormous attention of the science community for their possible applications in the fields of bioimaging and biomedicine. In this succession, various 0D structures including CdSe, CdTe, ZnS, graphene quantum dots (GQDs), carbon nanodots (CNDs) etc. have been explored for their possible applications in the field of biology. Recently, molybdenum disulfide quantum dots (MoS2-QDs) have been explored as an alternative of graphene quantum dots (GQDs) for their possible applications in relevant fields. Herein we report a facile, eco-friendly and single step hydrothermal synthesis of in-situ functionalized molybdenum disulfide quantum dots (f-MoS2-QDs). During the synthesis, variation in the pH of the starting solution provided the controlling over particle size. These as synthesized f-MoS2-QDs have shown excitation dependent broad emission spectra, which could be fitted for a parabolic function. The broadening in the emission spectra might be attributed to the polydispersity of f-MoS2-QDs in colloidal suspension, which was further confirmed with time resolved photoluminescence (TRPL) measurement. Due to surface capping provided by various functional groups present in the colloidal suspension, f-MoS2-QDs have shown excellent stability in aqueous medium and only a 3% of decrement in PL intensity was recorded even after six months. These synthesized f-MoS2-QDs possessed a quantum yield (QY) of 2.3% in aqueous media. Due to their high photostability and biocompatibility, these f-MoS2-QDs have been revealed as a potential entrant for in vivo bioimaging in Drosophila.

Graded Bandgap CsPbI2+xBr1−x Perovskite Solar Cells with a Stabilized Efficiency of 14.4%

Summary All-inorganic perovskite shows great potential for photovoltaic applications due to its excellent solar cell performance and atmospheric stability. Here, a CsPbI2+xBr1−x perovskite solar cell with a graded bandgap is explored using CsPbBrI2 and CsPbI3 quantum dots as component cells. Four strategies were pursued to boost the device performance. First, CsPbI2Br film was fabricated as the main absorber, with the component cell showing remarkable power conversion efficiency (PCE) as high as 13.45%. Second, by Mn2+ substitution, SCN− capping, and [(NH2)2CH]+ treatment, stable and high-mobility CsPbI3 quantum dot (QD) film was attained. Third, a halide-ion-profiled heterojunction was designed at the CsPbBrI2/CsPbI3 QD interface to achieve proper band-edge bending as graded bandgap for improved carrier collection. Finally, the CsPbI3 QD layer was optimized in the graded bandgap structure to achieve maximum overall light harvesting. As a result, the device achieved a PCE of 14.45%. This is the highest efficiency ever reported for inorganic perovskite solar cells.

Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands.

Long alkyl-chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light-emitting diodes (LEDs). The trade-off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr3 ) QDs with a conjugated alkyl-amine, 3-phenyl-2-propen-1-amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA-QDs films increased almost 22 times over that of OA-QD films without compromising colloidal stability and photoluminescence. PPA-QDs LEDs exhibit a maximum current efficiency of 9.08 cd A-1 , which is 8 times of that of OA-QDs LEDs (1.14 cd A-1 ). This work provides critical solution for the poor conductivity of QDs in applications of energy-related devices.

Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands

AbstractLong alkyl‐chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light‐emitting diodes (LEDs). The trade‐off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr3) QDs with a conjugated alkyl‐amine, 3‐phenyl‐2‐propen‐1‐amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA‐QDs films increased almost 22 times over that of OA‐QD films without compromising colloidal stability and photoluminescence. PPA‐QDs LEDs exhibit a maximum current efficiency of 9.08 cd A−1, which is 8 times of that of OA‐QDs LEDs (1.14 cd A−1). This work provides critical solution for the poor conductivity of QDs in applications of energy‐related devices.

Transient Spectroscopy of Glass-Embedded Perovskite Quantum Dots: Novel Structures in an Old Wrapping

Abstract Semiconductor doped glasses had been used by the research and engineering communities as color filters or saturable absorbers well before it was realized that their optical properties were defined by tiny specs of semiconductor matter known presently as quantum dots (QDs). Nowadays, the preferred type of QD samples are colloidal particles typically fabricated via organometallic chemical routines that allow for exquisite control of QD morphology, composition and surface properties. However, there is still a number of applications that would benefit from the availability of high-quality glass-based QD samples. These prospective applications include fiber optics, optically pumped lasers and amplifiers and luminescent solar concentrators (LSCs). In addition to being perfect optical materials, glass matrices could help enhance stability of QDs by isolating them from the environment and improving heat exchange with the outside medium. Here we conduct optical studies of a new type of all-inorganic CsPbBr3 perovskite QDs fabricated directly in glasses by high-temperature precipitation. These samples are virtually scattering free and exhibit excellent waveguiding properties which makes them well suited for applications in, for example, fiber optics and LSCs. However, the presently existing problem is their fairly low room-temperature emission quantum yields of only ca. 1%–2%. Here we investigate the reasons underlying the limited emissivity of these samples by conducting transient photoluminescence (PL) and absorption measurements across a range of temperatures from 20 to 300K. We observe that the low-temperature PL quantum yield of these samples can be as high as ~25%. However, it quickly drops (in a nearly linear fashion) with increasing temperature. Interestingly, contrary to traditional thermal quenching models, experimental observations cannot be explained in terms of a thermally activated nonradiative rate but rather suggest the existence of two distinct QD sub-ensembles of “emissive” and completely “nonemissive” particles. The temperature-induced variation in the PL efficiency is likely due to a structural transformation of the QD surfaces or interior leading to formation of extremely fast trapping sites or nonemissive phases resulting in conversion of emissive QDs into nonemissive. Thus, future efforts on improving emissivity of glass-based perovskite QD samples might focus on approaches for extending the range of stability of the low-temperature highly emissive structure/phase of the QDs up to room temperature.

Hydrothermal synthesis of bright and stable AgInS2 quantum dots with tunable visible emission

Highly luminescent AgInS2 quantum dots (AIS QDs) were synthesized via hydrothermal method using L-glutathione (GSH) and sodium citrate (SC) as ligands. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) results confirmed that the AIS QDs have tetragonal chalcopyrite structure with good crystallinity, and the average diameter was about 3–5 nm. In addition, the obtained AIS QDs exhibited tunable photoluminescence (PL) spectra ranging from 575 nm to 650 nm and the quantum yield (QY) could reach up to 21.6% with the Ag/In ratio of 1:4 without further processing. Moreover, the experimental results demonstrated that the AIS QDs had long fluorescence lifetimes and excellent storage stability, indicating their promising applications in light-emitting diode (LED) and biological imaging fields.