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Realization of Excitation Wavelength Independent Blue Emission of ZnO Quantum Dots with Intrinsic Defects
摘要： Eco-friendly cation metal oxide quantum dots (QDs) are one of promising candidates to replace for QDs containing expensive Indium (In) or hazardous Cd- and Pb-elements. Super-Eg excitation wavelength (λex) dependent Zni-VO complex defects related characteristic emissions of green, yellow, and orange-red from ZnO QDs are completely inhibited by reducing oxygen vacancies through the hybridization of Zn interstitials in ZnO QDs with anti-bonding O-states of graphene oxide (GO) QDs. Thus, only λex independent violet-purple-blue (V-P-B) emission resulting from transitions among Frenkel pairs (Zni 0-VZn) and the defects Zni 0-Oi in ZnO-GO QDs with a high photoluminescence quantum yield (PLQY) of 92% is successfully achieved. White-light emission from PL QD-LEDs is achieved using a mixture of ZnO and ZnO-GO QDs with CIE (0.32, 0.34) excited by a UV LEDs chip (λ=365 nm). Further, ZnO-GO QD-based deep-blue LEDs (λ=438 nm) with luminance of 1980 cd/m2, a luminous efficacy (LE) of 2.53 cd/A, and external quantum efficiency (EQE) of 2.78 % with CIE (0.16, 0.11) are also realized.
关键词： eco-friendly fluorescent materials,excitation independent deep blue light emission,photoluminescence quantum efficiency,Zni-Vo complex defects,ZnO-Graphene Oxide quantum dots
更新于2025-09-19 17:13:59
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An Eco-Friendly Disposable Plasmonic Sensor Based on Bacterial Cellulose and Gold
摘要： In several application fields, plasmonic sensor platforms combined with bio-receptors are intensively used to obtain biosensors. Most of these commercial devices are based on a disposable chip. Usually a gold chip, functionalized with a specific bio-receptor, inside a costly sensor system, is used. In this work, we propose a low-cost and small-size sensor system, used for monitoring a disposable plasmonic chip, based on an innovative optical waveguide made of bacterial cellulose (BC). In particular, we have sputtered gold on the green slab waveguide that is able to excite localized surface plasmon resonance (LSPR). Experimental results are presented on the capabilities of using the BC-based composite as an eco-friendly plasmonic sensor platform, which could be exploited for realizing disposable biosensors. The sensor has been used with optical fibers and simple equipment. More specifically, the fibers connect the green disposable LSPR sensor with a light source and with a spectrometer. The novel plasmonic sensing approach has been tested using two different optical waveguide configurations of BC, with and without ions inside BC.
关键词： bacterial cellulose,localized surface plasmon resonance,eco-friendly disposable sensors,optical sensors,sustainable development
更新于2025-09-16 10:30:52
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An eco-friendly imprinted polymer based on graphene quantum dots for fluorescent detection of <i>p</i> -nitroaniline
摘要： An eco-friendly fluorescent molecularly imprinted polymer anchored on the surface of graphene quantum dots (GQDs@MIP) was developed with an efficient sol–gel polymerization for highly sensitive and selective determination of p-nitroaniline (p-NA). The GQDs@MIP was characterized in detail by Fourier-transform infrared, fluorescence spectrometer, scanning electron microscope, transmission electron microscope and ultraviolet spectrophotometer. The results showed that the imprinted layer was successfully grafted on the surface of the GQDs. The fluorescence of the GQDs@MIP is efficiently quenched when p-NA recombines with the imprinting sites based on the photo-induced electron transfer fluorescence quenching mechanism. A good linear relationship was obtained between the fluorescence quenching efficiency of the GQDs@MIP and the concentration of p-NA in the range of 0–15.0 mM with a correlation coefficient of 0.99. The practicability of the proposed method in real samples was successfully evaluated through monitoring p-NA in water and fish samples with satisfactory recovery. The developed method provides a feasible and eco-friendly strategy to fabricate MIPs anchored on GQDs with good fluorescence properties for sensitive detection of organic pollutants in complex samples.
关键词： graphene quantum dots,fluorescent molecularly imprinted polymer,p-nitroaniline,fluorescence quenching,eco-friendly
更新于2025-09-16 10:30:52
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Aqueous-Soluble Naphthalene Diimide-Based Polymer Acceptors for Efficient and Air-Stable All-Polymer Solar Cells
摘要： Aqueous-processed all-polymer solar cells (aq-APSCs) are reported for the first time by developing a series of water/ethanol-soluble naphthalene diimide (NDI)-based polymer acceptors P(NDIDEG-T), P(NDITEG-T), and P(NDITEG-T2). Polymer acceptors are designed by using the backbones of NDI-bithiophene and NDI-thiophene in combination with non-ionic hydrophilic oligoethylene glycol (OEG) side chains that facilitate processability in water/ethanol mixtures. All three polymers exhibit sufficient solubility (20-50 mg mL?1) in the aqueous medium. The P(NDIDEG-T) polymer with shorter OEG side chains is the most crystalline with the highest electron mobility, enabling the fabrication of efficient aq-APSCs with the maximum power conversion efficiency (PCE) of 2.15%. Furthermore, these aq-APSCs are fabricated under ambient atmosphere by taking advantage of the eco-friendly aqueous process and, importantly, the devices exhibit outstanding air-stability without any encapsulation, as evident by maintaining more than 90% of the initial PCE in air after 4 days. According to a double cantilever beam test, the interfacial adhesion properties between the active layer and electron/hole transporting layers were remarkably improved by incorporating the hydrophilic OEG-attached photoactive layer, which hinders the delamination of the constituent layers and prevents the increase of series resistance, ultimately leading to enhanced durability under ambient conditions. The combination of increased device stability and minimized environmental impact of these aq-APSCs demonstrates them to be worthy candidates for continued development of scalable polymer solar cells.
关键词： eco-friendly solution process,aqueous process,air-stability,all-polymer solar cells,oligoethylene glycol (OEG) side chain
更新于2025-09-12 10:27:22
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ZnO@graphene QDs with tuned surface functionalities formed on eco-friendly keratin nanofiber textile for transparent and flexible ultraviolet photodetectors
摘要： We demonstrate the ZnO@graphene core@shell quantum dot (ZGQDs) fabricated by selectively engineering of oxygenated functional groups on the graphene shells with eco-friendly keratin textile for transparent and flexible UV photodetector devices. The ZGQDs with the octylamine (ZGQDs-OA) and the graphene sheet were employed as an active material and an electron transport channel. The functional groups on the surrounding graphene shell in ZGQDs were passivated by the OA, resulting in a good absorbance in UV light and excellent carrier transport properties. The passivation of the functional groups on the graphene shell by OA drastically enhanced the photocurrent. Optical transmittance of the ZGQDs-OA/graphene sheets/PMMA/keratin nanofiber textile composites structures was approximately 77 % at the visible spectrum range. Current–voltage (I-V) and current–time (I-t) measurements on the UV photodetector under illumination state in bending condition exhibited the excellent ON/OFF switching states and stability. The photosensitivity and responsivity of the photodetector with ZGQDs-OA were found to be around 13.10 and 68.64 μAmW-1, respectively, which is much higher than that without the passivation. The improved performance of the photodetector with ZGQDs-OA could be attributed to the efficient electron transport to the electrode by the passivation of the graphene on ZnO QDs.
关键词： ZnO@graphene QDs,flexible device,photodetector,Eco-friendly,Textile
更新于2025-09-12 10:27:22
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Eco-friendly and stable silver bismuth disulphide quantum dot solar cells via methyl acetate purification and modified ligand exchange
摘要： From the point of view of environmentally-friendly, non- or less toxic photovoltaic material and fabrication method are desired by both the academia and industrial community. However, most efficient quantum dot solar cells have been fabricated based on heavy metal and toxic solvent consumption, which could cause serious ecological problems. Quantum dot solar cells were studied and explored based on lead-free active material silver bismuth disulphide, less toxic solvent purification of methyl acetate and lab-developed ligand exchange process. Twice ligand exchanges with tetramethylammonium iodide were applied for every deposited quantum dot layer kept in static. Methanol rinse was applied to the quantum dot film after each ligand exchange process to promote the ligand exchange and clean the organic residuals. Decent power conversion efficiency and good stability were demonstrated for the fabricated silver bismuth disulphide quantum dot solar cells. The best power conversion efficiency of 4.57% was achieved, with open-circuit voltage of 0.445 V, short-circuit current of 18.87 mA/cm2 and fill factor of 54.4%. Over 95% of the original power conversion efficiency was maintained after 150 days both in N2-filled glove box and ambient atmosphere with relative humidity of 30%. This work demonstrated fabrication of quantum dot solar cells based on non- or less-toxic quantum dots and solvent consumption. Which would benefit the development and commercialization of quantum dot solar cell technology.
关键词： low-toxic solvent,silver bismuth disulphide,performance,eco-friendly solar cell,Lead-free quantum dots,ligand exchange
更新于2025-09-11 14:15:04
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MCM-SO3H catalyzed synthesis of environment-sensitive fluorophores incorporating pyrene moiety: Optimization, fluorescence emission and theoretical studies
摘要： Six new highly fluorescent 5-(aryl)-1-phenyl-3-(pyren-1yl)-2-pyrazolines were synthesized by reaction of various (E)-3-aryl-1-(pyren-1-yl)prop-2-en-1-ones with phenyl hydrazine in the presence of sulfonated mesoporous silica (MCM-SO3H) as efficient and eco-friendly acidic catalyst. The chemical structures of all synthesized compounds were illustrated on the basis of spectral data (IR, 1H NMR and 13C NMR). This was followed by photophysical properties-based absorption and emission studies of the target compounds in solutions of different solvent polarities. The microenvironment-sensitive fluorescent pyrazolines labeled with pyrene exhibited valuable fluorescence properties with emission in the range of 600–700 nm with a marked response to change in the environmental polarities. A significant and pronounced red shift was observed in the emission spectrum of 5-(aryl)-1-phenyl-3-(pyren-1yl)-2-pyrazolines Δλ ～ 50 nm compared to the absorption spectrum Δλ ～ 10 nm upon increasing the solvent polarity. This indicated the presence of higher dipole moment in the excited state than in the ground state and the transition involved are π-π* transition through the charge transfer phenomena. The fundamental understanding of solvatochromic properties were analyzed through Lippert-Mataga and Reichardts correlations in order to estimate the change in dipole moments (Δμ) which suggested the emissive state of designed fluorescent 2-pyrazoline derivatives is of strong ICT character.
关键词： Pyrene,Solvatochromic properties,Eco-friendly,2-Pyrazolines,Fluorophores,MCM-SO3H
更新于2025-09-10 09:29:36
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Reference Module in Materials Science and Materials Engineering || Film Deposition Processes Based on Eco-Friendly, Flexible, and Transparent Materials for High-Performance Resistive Switching
摘要： In 1971, the term memristor, the fourth fundamental element besides resistor, capacitor, and inductor was coined by Dr. Leon Chua. However, it was only in 2008 that Stanley Williams of Hewlett-Packard (HP) realized its existence for a device using TiO2 as the switching material and platinum (Pt) as electrodes. A two-terminal metal-insulator-metal (MIM) device has the ability of reversible resistive switching (RS) between low-resistance state (LRS) and high-resistance state (HRS) when an excitation voltage or current is applied. SET is de?ned to be a transition from HRS to LRS and corresponding voltage as Vset. On the other hand, RESET is de?ned as the transition from LRS to HRS and corresponding voltage as Vreset. Resistances in LRS and HRS are represented as RLRS and RHRS, respectively.
关键词： Transparent Electronics,Memristor,Eco-Friendly Materials,Film Deposition,Resistive Switching,Flexible Electronics
更新于2025-09-04 15:30:14