Concentration Of QDs Research Articles

Reduction of recombination at the interface of perovskite and electron transport layer with graded pt quantum dot doping in ambient air-processed perovskite solar cell

The study of charge transfer in thin film solar cells made of several layers is of high importance since they may lose their energy via the recombination process at the interfaces, specifically at the interface of the electron transport layer (ETL) and perovskite. Titanium dioxide (TiO2) is mostly used as an ETL in perovskite solar cells due to its many advantages. However, TiO2 has some disadvantages, such as low electron mobility compared to the perovskite layer and electron trap states on its top at the interface. These effects cause the accumulation of carriers at the ETL/perovskite interface then the non-radiative recombination will be enhanced, which is considered as one of the significant losses in the Perovskite Solar Cells (PSCs). In this work, a new technique is taken for more optimal ETL doping. We fabricated the ETL layers with graded doping of platinum quantum dots (Pt QDs), in which Pt QDs concentration is high at the ETL/Perovskite interface and zero at the FTO/ETL interface. This strategy not only suppresses the recombination at the ETL/perovskite interface and subsequently enhances the device efficiency from 12.92 to 14.36% but also improves the stability of the PSCs.

Graphene quantum dots as eco-friendly fluorescent probes for sensitive and selective determination of lumateperone in pharmaceutical preparation: Greenness and blueness assessment

This study investigates the potential of graphene quantum dots (GQDs) as fluorescent probes for the determination of the antipsychotic drug lumateperone. The spectral characteristics and sensing mechanism of the fluorescent probes were examined, revealing a static quenching mechanism as indicated by the Stern-Volmer analysis. Different factors affecting the quenching process, such as pH, concentration of QDs, and incubation time, were carefully tuned. The developed method was validated according to ICH guidelines, demonstrating excellent linearity in the range of 0.5–2.5 μg/mL, limits of detection and quantification of 0.1226 μg/mL and 0.3714 μg/mL, respectively, and high accuracy, precision, robustness and selectivity. Furthermore, the greenness and blueness of the proposed method were assessed using GAPI, AGREE, and BAGI tools, yielding an AGREE score of 0.78 and a BAGI score of 75 confirming its environmentally benign nature as well as analytical practicality. The method was successfully applied to determine lumateperone in a pharmaceutical formulation, highlighting its potential for routine quality control analysis. This study demonstrates the promising analytical capabilities of GQDs for the sensitive and selective detection of antipsychotic drug lumateperone, offering a simple, rapid, and green alternative to existing analytical techniques.

Ag quantum dots-doped poly (vinyl alcohol)/chitosan hydrogel coatings to prevent catheter-associated urinary tract infections

The prevention of catheter-associated urinary tract infections (CAUTIs) significantly impacts the reduction of morbidity and mortality associated with the use of indwelling urinary catheters. This study focused on developing an antibacterial double network hydrogel coating for latex urinary catheters, which incorporated Ag quantum dots (Ag QDs) in a polyvinyl alcohol (PVA)-chitosan (CS) double network hydrogel matrix. The PVA-CS-Ag QDs, referred to as the PCA hydrogel coating exhibited excellent mechanical and physiochemical properties with controlled release of Ag QDs. The antibacterial properties of the PCA hydrogel-coated urinary catheters were studied against both gram-negative Escherichia coli (E. coli, ATCC25922) and gram-positive Staphylococcus aureus (S. aureus, ATCC29213). The continuous release of CS oligomers and Ag QDs from the hydrogel coating contributed to the synergistic antibacterial and antiadhesion effects. Measurements of the Ag release rate revealed that even after 30 days, the concentration of Ag QDs from the PCA hydrogel-coated urinary catheters remained significantly higher than the effective antibacterial concentration of the total Ag (0.1 μg·L−1). These results indicated that the PCA hydrogel coating not only efficiently prevented bacteria attachment, but also exhibited long-term antibacterial activity, thereby inhibiting biofilm formation. Furthermore, the PCA hydrogel-coated urinary catheter demonstrated excellent biocompatibility and hemocompatibility. Overall, this novel PCA hydrogel-coated urinary catheter, with its exceptional antibacterial properties, holds great potential in reducing the incidence of CAUTIs.

Competent CuS QDs@Fe MIL101 heterojunction for Sunlight-driven degradation of pharmaceutical contaminants from wastewater

In this study, we introduce an advanced photocatalyst developed by integrating copper sulfide quantum dots (CuS QDs) with an iron-based metal–organic framework (MOF), specifically Fe MIL101. The resulting CuS QDs@Fe MIL101 photocatalyst is engineered to efficiently degrade meloxicam (MLX) under simulated sunlight. The heterojunctions were generated by incorporating different concentrations of CuS QDs (5 %, 10 %, 15 %, 20 %, and 50 %) into the Fe MIL101 MOF matrix using the microwave-assisted hydrothermal method. The results of the XRD and the TEM studies confirmed the formation of the heterojunctions, which maintain the structural integrity of both CuS QDs and Fe MIL101. The BET measurements indicated a decrease in surface area upon CuS QDs incorporation, attributed to porés blockage and structural modifications. UV–Vis diffuse reflectance spectroscopy (DRS) revealed a redshift in absorption edges as CuS QDs content increased, enhancing visible light absorption. Photoluminescence (PL) investigations revealed that the 15 % CuS QDs@Fe MIL101 heterojunction had an effective charge separation and low recombination rates. The zeta potential analysis revealed a negative surface charge, indicating an overall electronegative characteristic. The photocatalytic performance, assessed through the degradation of MLX, demonstrated that the 15 % CuS QDs@Fe MIL101 heterojunction achieved the maximum degradation efficiency, reaching 96 % after 45 min of irradiation at a dosage of 0.1 g/L. This exceptional performance is attributed to potent charge separation, improving visible light absorption, high surface area and adsorption capacity. Various scavengers were used to investigate the roles of different reactive species, revealing holes as the predominant active species in the photocatalytic degradation process. These results highlight the potential of 15 % CuS QDs@Fe MIL101 heterojunctions as efficient photocatalyst for environmental remediation from pharmaceutical pollutants under simulated sunlight. These findings highlight the potential for application of CuS QDs@Fe MIL101 in real-world wastewater treatment systems, particularly in addressing pharmaceutical contaminants like meloxicam in industrial effluents.

Implementation of a Fractional-Inductor (α

In this paper, the realization of a fractional-order inductor of order less than 0.5 has been realized, where, semiconducting Quantum dots of Zirconium (Zr QDs) is the key component. When a TEM (Transverse Electromagnetic Mode) is used to design a fractional-inductor using a conducting core, it yields a fractional order of 0.5 which is also mathematically derived in this work. Here, in place of conducting fluid, different concentrations of Zr QDs in ethanol have been used which show different phase shifts of the current (less than 45°) with respect to voltages. These experimentally found results, confirm the realization of fractional-inductor of order α < 0.5.The fabricated device works perfectly with a temperature range of −10 °C to 45 °C with an aging of ≈ 1.5 years. Also, the fabricated inductor has been used in an integrating circuit, which shows the change in roll-off-rate, and cut-off-frequency variations with respect to the variation in concentration of Zr QDs in the ethanol solution as the core of fractional-inductor. These experimental values show a good agreement with the simulation with a maximum error percentage of 10 %.

Anticancer effects of pH- sensitive carvacrol zinc oxide quantum dots on DMBA induced mammary carcinoma in female sprague dawley rats

ObjectivesThe current research explores the anticancer effects of pH sensitive CVC-ZnO QDs (Carvacrol-loaded Zinc Oxide Quantum Dots) on DMBA induced mammary carcinoma in rats. MethodsFemale SD rats were used, and mammary cancer was induced by chemical carcinogen via subcutaneous injection near the mammary gland. Different concentrations of CVC-ZnO QDs were orally supplemented to evaluate the optimum dose. We assessed the growth rate, body weight changes, tumor volume, tumor incidence and tumor burden in both the inducer and treatment groups. We also evaluated the biochemical parameters (antioxidant status, lipid peroxidation, detoxification enzymes, and lipid profile) and histopathological changes in the kidney and mammary tissues. ResultsOur findings indicate that CVC-ZnO QDs treated rats significantly decreased the tumor weight, incidence, burden, lipid peroxidation levels, phase I detoxification enzyme activities and increased the body weight, phase II detoxification enzyme activities, and antioxidant status compared to the DMBA alone treated rats. CVC-ZnO QDs treatment also altered the lipid profile of plasma and mammary tissue. Furthermore, histopathological results confirmed that the CVC-ZnO QDs protect against DMBA-mediated damage to the mammary and kidney. ConclusionThe findings indicate that the CVC-ZnO QDs administered at 4 mg/kg b.w exhibited a significant anticancer effect against DMBA-induced mammary cancer.

Improving Organic Photovoltaic Efficiency via Heterophase Homojunction Copper Indium Sulfide Nanocrystals

Eco‐friendly heterophase homojunction copper indium sulfide quantum dots (HH‐CIS QDs) terminated by short hydroxyl ligands are integrated into nonfullerene organic solar cells (OSCs) for the first time. Experimental results exhibit that this novel nanostructure can improve sunlight absorption and charge transfer ability, harvesting more photons and converting them to charge carriers. Additionally, the formation of hydrogen bonds between 2‐mercaptoethanol‐capped HH‐CIS QDs and the interface modification layer is beneficial for better interfacial contact, which promotes work function modification, reduces surface roughness, and increases interfacial charge transfer. Benefiting from HH‐CIS QDs incorporation, nonfullerene OSCs involving two different types of photoactive layers and three different types of electron transport layers all demonstrate improved photoelectric conversion efficiency (PCE). With QDs concentration optimization, nonfullerene OSCs with the PM6:ITIC‐4F and PM6:Y6 absorbers exhibit excellent PCEs of 14.04% and 16.26%, respectively. As compared to those reported previously, HH‐CIS QDs into the interface between the electron charge layer and photoactive layer lead to significant performance improvement, with both achieve PCEs and enhancement factors among the highest ones reported for various QD‐integrated OSCs. The results strongly suggest that the rational design of QDs and their optimal integration are critical for performance enhancement.

Green Synthesis, Characterization, and Acoustical Analysis of Copper Quantum Dots (Cu QDs) Using Leaf Extract of Mangifera indica Plant

The copper quantum dots (Cu QDs) are successfully green synthesized from copper sulfate (CuSO[Formula: see text] as precursor material using plant leaf extracts of Mangifera indica. The mangiferin as a natural glucosylxanthone present in leaf extract of M. indica acquires antioxidant, antimicrobial, antidiabetic, antiallergic, anticancer, hypocholesterolemic, and immunomodulatory activity, which acts as an effective stabilizing and reducing agent for conversion of the copper ion (Cu[Formula: see text] into the Cu QDs in aqueous medium. The green synthesized Cu QDs are characterized using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, dynamic light scattering instrumental techniques, which confirm the successful synthesis and photoluminescence (PL) behavior of the Cu QDs. The ultrasonic investigation was carried out to find out the variation of ultrasonic velocity and density with concentration of Cu QDs in aqueous leaf extracts of M. indica plant as well as to calculate the dependency of acoustical parameter, namely adiabatic compressibility, acoustic impedance, and intermolecular free length on concentrations. The synthesized Cu QDs are biocompatible that can be a potential candidate for various in vivo and in vitro applications such as antioxidant, antimicrobial, anticancer, biosensor, bioimaging, and biocatalysis fields.

Rapid One-Pot Microwave Assisted Green Synthesis Nitrogen Doped Carbon Quantum Dots as Fluorescent Precursor for Estimation of Modafinil as Post-Covid Neurological Drug in Human Plasma with Greenness Assessments

The neuro-stimulant anti-narcoleptic drug as modafinil (MOD) is used to treatment neurological conditions caused by COVID-19. MOD was used to treatment narcolepsy, shift-work sleep disorder, and obstructive sleep apnea-related sleepiness. So, an innovative, quick, economical, selective, and ecologically friendly procedure was carried out. A highly sensitive N@CQDs technique was created from green Eruca sativa leaves in about 4 min using microwave synthesis at 700 w. The quantum yield of the synthesized N@CQDs was found to be 41.39%. By increasing the concentration of MOD, the quantum dots' fluorescence intensity was gradually quenched. After being excited at 445 nm, the fluorescence reading was recorded at 515 nm. The linear range was found to be in the range 50 – 700 ng mL−1 with lower limit of quantitation (LOQ) equal to 45.00 ng mL−1. The current method was fully validated and bio analytically according to (US-FDA and ICH) guidelines. Full characterization of the N@CQDs has been conducted by high resolution transmission electron microscope (HRTEM), Zeta potential measurement, fluorescence, UV–VIS, and FTIR spectroscopy. Various experimental variables including pH, QDs concentration and the reaction time were optimized. The proposed study is simply implemented for the therapeutic drug monitoring system (TDMS) and various clinical laboratories for further pharmacokinetic research.

Development of antimicrobial nanocomposite scaffolds via loading CZTSe quantum dots for wound dressing applications

The antimicrobial properties of scaffolds designed for use in wound healing are accepted as an important factor in the healing process to accelerate the wound healing process without causing inflammation. For this purpose, chitosan–polyvinyl alcohol composite membranes loaded with Cu2ZnSnSe4 quantum dots (CZTSe QDs) as an antibacterial and cytocompatible biomaterial to regulate the wound healing process were produced. CZTSe QDs particles were synthesized under hydrothermal conditions. Polymer-based nanocomposites with different concentrations of the synthesized nanoparticles were produced by the solvent casting method. After detailed physicochemical and morphological characterizations of CZTSe QDs and composite membranes, antibacterial activities and cell viability were extensively investigated against gram-positive and gram-negative bacterial and yeast strains, and L929 mouse fibroblast cells lines, respectively. The results show that the preparation of composite scaffolds at a QDs concentration of 3.3% by weight has the best antimicrobial activity. Composite scaffold membranes, which can be obtained as a result of an easy production process, are thought to have great potential applications in tissue engineering as wound dressing material due to their high mechanical properties, wettability, strong antibacterial properties and non-toxicity.

A novel fabrication strategy for alloyed Cd–Zn–S quantum dots–embedded glass with efficient red emission

AbstractQuantum dots–embedded glasses (QDEGs) can combine the unique optical properties of QDs with high physicochemical stability and good mechanical properties of glasses, which have been widely investigated and applied in lighting and display. However, precise controlling the concentration and size distribution of QDs, and precipitating QDs with desired compositions or multicomponents in glass are still challenges for the traditional melt‐quenching method. Herein, a series of alloyed Cd–Zn–S QDEGs from green to red emission is successfully prepared via a novel fabrication strategy for the first time. Specifically, the solid‐solution precursors crack during the sintering process to form the well‐dispersed QDs with a narrow distribution, attributing to the gradient sulfur composition and the shearing force induced by the thermal migration of sulfur vacancies. Significantly, the quantum yield of Cd0.5Zn0.5S QDEG could reach 30%, among the top results of efficient red‐emissive QDEG materials. Finally, using QDEGs as light converters, a UV‐pumped warm white light–emitting diode with a correlated color temperature of 4238 K was achieved, which demonstrate the potential applications of the alloyed Cd–Zn–S QDEGs. These results will inspire more explorations on this fabrication strategy to develop novel QDEGs with a high optical performance for practical applications.

Titanate quantum dots-sensitized Cu2S nanocomposites for superficial H2 production via photocatalytic water splitting

TiO2 quantum dots-sensitized Cu2S (Cu2S/TiO2) nanocomposites with varying concentration of TiO2 QDs are synthesized via a facile two-stage hydrothermal-wet impregnation method. X-ray diffraction analysis confirms the formation of Cu2S and TiO2with chalcocite and anatase phases, respectively. The observed shoulder-like absorption peaks indicate the UV–visible light-driven properties of the composite. Morphological analysis reveals that the fabricated Cu2S/TiO2 composite consists of Cu2S with a nano rod-like shape (average length and width of ∼856 and ∼213 nm, respectively) and nanosheets-like structures (average length and width of ∼283 and ∼289 nm, respectively), whereas the TiO2 is formed as quantum dots with a size range of 8.2 ± 0.4 nm. Chemical state analysis shows the presence of Cu+, S2−, Ni2+, and O2− in the nanocomposite. The H2 evolution rate over the optimized photocatalyst is found to be ∼45.6 mmol h−1g−1cat under simulated solar irradiation, which is around 5 and 2.4-fold higher than that of the pristine TiO2 and Cu2S, respectively. Continuous H2 production for 30 h is achieved during time-on-stream experiments, demonstrating the excellent stability and durability of the Cu2S/TiO2 photocatalyst for large-scale applications.

Dielectric and electro-optical properties of nematic liquid crystal p-methoxybenzylidene p-decylaniline dispersed with oil palm leaf based porous carbon quantum dots

The effect of dispersing oil palm leaf-based porous carbon quantum dots (OPL QDs) in nematic liquid crystal p-methoxybenzylidene p-decylaniline (MBDA) has been studied in this paper. The dielectric properties were measured with and without bias voltage as a function of frequency and temperature. Electro-optical parameters like response time, rotational viscosity and birefringence have also been studied with respect to temperature and OPL QDs concentration. The main findings show that when the dispersion of OPL QDs increases, the sign of dielectric anisotropy changes. Fall time has been found to be faster than the rise time for pure MBDA, composites 1 and 2, while composites 3 to 5 have faster rise time than fall time. This has been due to a change in the sign of dielectric anisotropy that begins from composite 3. UV-VIS absorbance and photoluminescence studies have been carried out which demonstrates the existence of π–π* transition. The remarkable outcomes of this work can be applied in the display and photonics field.

Pharmacokinetics, tissue distribution and peritoneal retention of Ag2S quantum dots following intraperitoneal administration to mice.

To investigate the pharmacokinetics, biodistribution and peritoneal retention of Ag2S quantum dots (Qds) after intraperitoneal (IP) injection into mice and to compare the results with those reported for the intravenous (IV) injection of these particles. Ag2S Qds was prepared by a simple one-step co-precipitation method and was injected intraperitoneally into mice. Six animals were sacrificed at predetermined time points, and blood, peritoneal content and tissue samples were collected. Ag concentration that represents the concentration of Qds was analysed by atomic absorption spectrophotometry. Detectability of Qds in the peritoneal sample up to 2 h indicated that, compared with small drug molecules, the absorption of Ag2S Qds from the peritoneal cavity occurred at a slower rate. The AUC tissue/AUC blood ratio in the liver and intestine after IP injection (0.55 and 0.98, respectively) was considerably lower than those for the bolus injection (217 and 94, respectively), while this ratio in the spleen and lungs was markedly higher than the IV route. Overall, the obtained results suggest that IP injection of Ag2S Qds could be more effective for drug delivery to/imaging of the spleen and lungs, whereas the IV injection for the drug delivery to/imaging of the liver and intestine.

Preparation of AgInS2 quantum dots and their application for Pb2+ detection based on fluorescence quenching effect

Water soluble AgInS2 quantum dots (AIS QDs) were successfully prepared by an environmentally friendly one-pot water phase method using glutathione (GSH) as the stabilizing agent. The crystal structure, morphology, size, chemical states, and optical properties of as-prepared AIS QDs were characterized through X-ray diffraction (XRD), Scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR), Ultraviolet–visible spectrophotometer (UV–vis) and Photoluminescence spectrometer (PL). Factors affecting the fluorescence intensity of AIS QDs including reaction solution pH value, fluorescence test temperature and concentration of AIS QDs were investigated. The fluorescence stability of AIS QDs and the selectivity of AIS QDs toward Pb2+ detection was also evaluated. Under optimized test conditions, three excellent linear relationships ((F0−F)/F0=27.938CPb2+−0.002(R=0.998), (F0−F)/F0=10.362CPb2+−0.005(R=0.997), (F0−F)/F0=6.554CPb2+−0.240(R=0.9993) were achieved between the concentration of Pb2+ and the relative fluorescence quenching amount of AIS QDs in the range of 9–96 nM, 48–434 nM and 193–530 nM, respectively. The detection limit was 4 nM and the recovery was in the range of 92.2%–102.6%. Our method had wide detection range, excellent selectivity, high sensitivity and easy operability, and could be applied for the content determination of Pb2+ in water. The possible fluorescence quenching mechanism of AIS QDs by Pb2+ was discussed in detail and the dynamic quenching mechanism of light-induced electron transfer was put forward.

Synergism of Zinc Oxide Quantum Dots with Antifungal Drugs: Potential Approach for Combination Therapy against Drug Resistant Candida albicans

Candidiasis caused by Candida albicans is one of the most common microbial infections. Azoles, polyenes, allylamines, and echinocandins are classes of antifungals used for treating Candida infections. Standard drug doses often become ineffective due to the emergence of multidrug resistance (MDR). This leads to the use of higher drug doses for prolonged duration, resulting in severe toxicity (nephrotoxicity and liver damage) in humans. However, combination therapy using very low concentrations of two or more antifungal agents together, can lower such toxicity and limit evolution of drug resistance. Herein, 4–6 nm zinc oxide quantum dots (ZnO QDs) were synthesized and their in vitro antifungal activities were assessed against drug-susceptible (G1, F1, and GU4) and resistant (G5, F5, and GU5) isolates of C. albicans. In broth microdilution assay, ZnO QDs exhibited dose dependent growth inhibition between 0 – 200 µg/ml and almost 90% growth was inhibited in all Candida strains at 200 µg/ml of ZnO QDs. Synergy between ZnO QDs and antifungal drugs at sub-inhibitory concentrations of each was assessed by checkerboard analysis and expressed in terms of the fractional inhibitory concentration (FIC) index. ZnO QDs were used with two different classes of antifungals (azoles and polyenes) against Candida isolates: combination 1 (with fluconazole); combination 2 (with ketoconazole); combination 3 (with amphotericin B), and combination 4 (with nystatin). Results demonstrated that the potency of combinations of ZnO QDs with antifungal drugs even at very low concentrations of each was higher than their individual activities against the fungal isolates. The FIC index was found to be less than 0.5 for all combinations in the checkerboard assay, which confirmed synergism between sub-inhibitory concentrations of ZnO QDs (25 µg/ml) and individual antifungal drugs. Synergism was further confirmed by spot assay where cell viabilities of Candida strains were significantly reduced in all combinations, which was clearly evident from the disappearance of fungal cells on agar plates containing antifungal combinations. For safer clinical use, the in vitro cytotoxic activity of ZnO QDs was assessed against HeLa cell line and it was found that ZnO QDs were non-toxic at 25 µg/ml. Results suggested that the combination of ZnO QDs with drugs potentiate antimicrobial activity through multitargeted action. ZnO QDs could therefore offer a versatile alternative in combination therapy against MDR fungal pathogens, wherein lowering drug concentrations could reduce toxicity and their multitargeted action could limit evolution of fungal drug resistance.

Dose-Dependent Effect of ZnO Quantum Dots for Lettuce Growth.

As the cadmium-free semiconductor quantum dots, ZnO quantum dots (ZnO QDs) have wide potential applications in agriculture. However, the effects of ZnO quantum dots on crop growth and nutritional quality have not been fully studied. In this work, the lettuce was sprayed with different concentrations of ZnO QDs from 50 to 500 mg·L–1 to evaluate their influence on lettuce antioxidant, biomass, and nutritional quality. The results showed that ZnO QDs existed in the lettuce in the form of Zn2+. Lettuce treated with 500 mg·L–1 ZnO QDs would produce a large amount of reactive oxygen species (ROS), which adversely affected the absorption of nutrients, soluble protein content, and chlorophyll content, thus reducing plant biomass. When the concentrations range from 50 to 200 mg·L–1, the antioxidant enzyme systems of lettuce were triggered to counteract the damage caused by excessive ROS. Moreover, ZnO QDs at this level promoted Ca, Mg, Fe, Mn, Zn, and B absorption and accumulation; increased soluble sugar content; and improved the lettuce biomass and nutritional quality.

Effect of carbonaceous oil palm leaf quantum dot dispersion in nematic liquid crystal on zeta potential, optical texture and dielectric properties

In the present work, the dispersion of oil palm leaf based carbonaceous quantum dots (OPL QDs) in nematic liquid crystal (NLC) E 48 eutectic mixture has been reported. The dispersed systems with concentrations 0.1, 0.2, and 0.3 wt% are designated respectively, as MIX 1, MIX 2, and MIX 3. The objective of this study is to analyze the results on the zeta potential, optical texture, dielectric constant, dielectric loss, conductivity, dielectric strength, relaxation frequency, specific power loss and total power loss of pure and OPL QDs dispersed nematic E 48 system. Zeta potential measurement has been performed in the solution state to ensure dispersion stability. The optical textures and dielectric results are recorded after filling the respective samples in sample cells. The core findings in the present study show that the zeta potential varies from − 23.43 mV to + 28.07 mV that signifies the stability of OPL QDs suspension in LCs. Specific power loss (SPL) and total power loss (TPL) are found to be least for MIX 1 which shows that the problem of high power consumption in LCDs can be resolved by dispersing a small weight percent concentration of OPL QDs in LC medium (MIX 1). Improved molecular alignment in the dispersed system has been observed from the textural study which finds its application in good contrast display devices. The color change in the aligned textures with temperature has been attributed to the birefringence change. The porous nature of carbonaceous OPL QDs has its application in supercapacitors. The benchmark results of this study highlight the effect of temperature and frequency on dielectric parameters for both planar and homeotropic state of E 48 LCs. OPL QDs dispersed system display increased conductivity for MIX 3. The decrease in the activation energy for OPL QDs dispersed system in comparison to pure LC material E 48 is a consequential result of the potential barrier change. The increment in the dielectric strength and relaxation frequency of OPL QDs dispersed system is noticed in comparison to pure E 48. These outcomes open the door for the applicability of present LCs in the field of both display and non-display devices like sensors, supercapacitors, low power consumption displays, energy conversion, and electrical storage devices as well as advanced smart systems.

Graphitic carbon nitride quantum dots (g-C3N4) to improve photovoltaic performance of polymer solar cell by combining Förster resonance energy transfer (FRET) and morphological effects

In this study, multifunctionality of graphitic carbon nitride quantum dots (g-C3N4 QDs) have been explored as a photovoltaic booster for polymer solar cell. Facile synthesis method of g-C3N4 QDs using organic solvent like o-dichlorobenzene which is commonly used for cell fabrication, has been demonstrated. Photovoltaic effect formation and various effects of QDs on energy transfer, carrier transport and nanoscale film morphology of the devices have been investigated thoroughly by incorporating g-C3N4 QDs as a third component into a well-established material combination of P3HT: PC71BM blend films. While systematic variation of device performances was observed with varying concentration of QDs, at an optimal concentration of 2%, almost 40% performance improvement was achieved compared to the pristine devices. The g-C3N4 QDs were found to assist Förster resonance energy transfer (FRET) between the QDs and host polymer, improving overall energy harvesting capability of the devices. The emission spectra of g-C3N4 QDs (λEms = 400–550) and absorption spectra of P3HT (λAbs = 400–600) were found to have overlapping features which enabled the QDs to transfer ultraviolet region photon energy to P3HT. The g-C3N4 QDs were also found to be favorable for maintaining nanoscale phase segregation of the active layer with improved crystallinity which is crucial for efficient exciton dissociation and faster charge extraction. The enhanced power conversion efficiency thus attributed to the combined consequences of improved morphology and FRET effect. This study opens new prospects for developing high-efficiency solution processable photovoltaic devices using g-C3N4 QDs as the third component of the active layer.

Toxicity Evaluation of Quantum Dots (ZnS and CdS) Singly and Combined in Zebrafish (Danio rerio).

The exponential growth of nanotechnology has led to the production of large quantities of nanomaterials for numerous industrial, technological, agricultural, environmental, food and many other applications. However, this huge production has raised growing concerns about the adverse effects that the release of these nanomaterials may have on the environment and on living organisms. Regarding the effects of QDs on aquatic organisms, existing data is scarce and often contradictory. Thus, more information is needed to understand the mechanisms associated with the potential toxicity of these nanomaterials in the aquatic environment. The toxicity of QDs (ZnS and CdS) was evaluated in the freshwater fish Danio rerio. The fishes were exposed for seven days to different concentrations of QDs (10, 100 and 1000 µg/L) individually and combined. Oxidative stress enzymes (catalase, superoxide dismutase and glutathione S-transferase), lipid peroxidation, HSP70 and total ubiquitin were assessed. In general, results suggest low to moderate toxicity as shown by the increase in catalase activity and lipid peroxidation levels. The QDs (ZnS and CdS) appear to cause more adverse effects singly than when tested combined. However, LPO results suggest that exposure to CdS singly caused more oxidative stress in zebrafish than ZnS or when the two QDs were tested combined. Levels of Zn and Cd measured in fish tissues indicate that both elements were bioaccumulated by fish and the concentrations increased in tissues according to the concentrations tested. The increase in HSP70 measured in fish exposed to 100 µg ZnS-QDs/L may be associated with high levels of Zn determined in fish tissues. No significant changes were detected for total ubiquitin. More experiments should be performed to fully understand the effects of QDs exposure to aquatic biota.