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Benzothiazole pyrazole containing emissive azo dyes decorated with ESIPT core: Linear and non linear optical properties, Z scan, optical limiting, laser damage threshold with comparative DFT studies
摘要： Positional isomers of "benzothiazoles-pyrazole based azo dyes containing separate with ESIPT core" are analyzed for their "linear and non-linear optical (NLO)" properties. Dyes are emissive in ACN having Stokes shift in the range of 75 nm. Spectroscopic properties are further utilized to calculate band gap by CV. Band gap obtained by DFT and cyclic voltammetry (CV) are in good agreement with each other. Vertical excitation in six different functionals is compared with experimental absorption maxima. Non-linear absorptive coef?cient (b), nonlinear refractive index (?2), third-order non-linear optical suscep- tibility (c3) and optical limiting (OL) in acetone, ethanol and DMSO are obtained using Z-scan technique and results are appreciable than previously reported dyes. Satisfactory laser damage threshold (LDT) values are in the range of 7.9e9.7 (cid:1) 1013 W/m2. TGA study indicates that these compounds are useful in several high-temperature processes in the construction of electronic and optical devices. The geometry of the dyes are optimized at "B3LYP/6-311 t G (d,p) level". "Molecular Electrostatic Potential" (MEP), "Frontier Molecular Orbitals" (FMO) are presented using "Density Functional Theory (DFT)" to gain structural insights. Relatively new electrophilicity descriptor- "Hyperhardness" for both the molecules are calculated which suggests the stability of molecules. Global hybrid (GH) functional (B3LYP, BHandHLYP) and range separated hybrid (RSH) (CAM-B3LYP, uB97, uB97X, and uB97XD) functional are used to calculate linear and NLO properties. uB97 is a more suitable functional observed for determining bo and g. Direct relation in-between "dipole moment" (m) and "linear polarizability" (a) is also presented. These dyes can emerge as attractive NLOphores in optoelectronic applications.
关键词： ESIPT,NLO,Z-scan,LDT,DFT,Emissive azo dyes,Benzothiazole-pyrazole
更新于2025-09-11 14:15:04
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Investigation on Spectroscopic and Laser Properties of Pyrromethene and Perylene Chromophores in Elastic Polymeric Hosts
摘要： In this work, two types of chromophore i.e. the pyrromethene and perylene families dyes were doped into elastic polymeric host materials based on polydimethylsiloxane (PDMS), which had been widely employed in various applications. The solubilities, spectroscopic and laser properties of these dyes doped into PDMS matrices were systematically investigated. Tunable laser output with high conversion efficiencies and low laser thresholds were observed and calculated. The laser longevity of pyrromethene dyes doped in PDMS matrices could exceed 1 (cid:2) 105 pulses through a fast self-recovery on the laser output with the elapse of aging time. The efficient and stable laser output of the dopants and the flexibility of the PDMS host provided the feasibility of such gain media as mechanically tunable laser sources, which might be employed as cost-effective components on integrated bio-chips.
关键词： Polydimethylsiloxane (PDMS),Laser lifetime,Self-recovery,Dyes,Laser chemistry
更新于2025-09-11 14:15:04
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Using Polymers and Pigments to Produce Laser Interference Rings
摘要： When a laser of su?cient intensity is shined into a pigmented transparent medium, the partially absorbed laser light can heat and change the refractive index of the medium in the path of the beam. This altered medium will in turn cause the transmitted laser light to thermally defocus into a series of concentric rings. Some solvents such as 2-propanol and a variety of polymers such as polystyrene, polyethylene terephthalate, and polydimethylsiloxane can be pigmented with a variety of colors. Samples of various colors can be used to spectacularly demonstrate characteristics of light absorption. For example, a 2-propanol solution containing methyl red in red acidic form will absorb a green laser and produce interference rings, but a solution of methyl red in yellow basic form will not. As another example, a red laser beam will pass una?ected through a red pigmented ?lm, but the beam will heat a green ?lm (e.g., from a green pigmented polyethylene terephthalate soda bottle) to produce interference rings. Additionally, since the pattern produced is based on the interference of light waves, these demonstrations reinforce concepts associated with the wave nature of light.
关键词： Dyes/Pigments,Demonstrations,General Public,Analogies/Transfer,First-Year Undergraduate/General,Lasers
更新于2025-09-11 14:15:04
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Clitoria ternatea flower as natural dyes for Dye-sensitized solar cells
摘要： Clitoria ternatea flowers have been investigated as a natural sensitizer in Dye-sensitized solar cell (DSSC). Dried C. ternatea flowers ware immersed in ethanol for 48 hours in dark room to obtain anthocyanin pigments. We compared the photovoltaic performance of the sensitizers with Titanium dioxide (TiO2) only and TiO2 with scattering layers. C. ternatea dyes have higher Power Conversion Efficiency (PCE) when applied in TiO2 with scattering layers compared to standard TiO2 semiconductors. Scattering layer (SL) has increased the light path inside the photo-anode film that doubled the short-circuit current (Jsc) and enhanced the open circuit voltage (Voc) compared to TiO2 based cell without the SL. In conclusion, from the result, higher electron injections can be achieved by light management on photo-anode film with scattering layers as one of strategy to enhance the efficiency for further low cost and environment-friendly solar cell.
关键词： Dye-sensitized solar cells,Clitoria ternatea,TiO2,scattering layers,natural dyes
更新于2025-09-11 14:15:04
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One-pot microwave-assisted green synthesis of amine-functionalized graphene quantum dots for high visible light photocatalytic application
摘要： Nowadays, graphene quantum dots (GQDs) have gained a huge interest in the field of visible-range photocatalysts because of their tunable band gap and stable photochemical properties. In this work, amine-functionalized GQDs (AGQDs) were successfully prepared by one-step microwave-assisted conversion of glucose, H2O2, and NH3 solution. The obtained quantum dots possess the high quality of graphene structure with the average size of 3.78 nm as well as exhibit a strong green fluorescence with a high quantum yield. Interestingly, the amine-functionalized dots perform outstanding visible-light absorption. To further investigate photocatalytic properties, a composite of AGQDs and TiO2 was then prepared by a simple mixing route. The hybrid material showed high catalytic activity of dye degradation under visible light irradiation, which indicates the key role of AGQDs in enhancing light absorption and induced electron-hole separation. The current study may open a new way for construction of effective visible light photocatalytic systems with a cost-effective, simple approach.
关键词： Fluorescent visible light photocatalyst,Graphene quantum dots,Amine functionalized,Dyes photodegradation
更新于2025-09-11 14:15:04
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Synthesis and investigation of double alternating azo group in novel para-azo dyes containing nitro anchoring group for solar cell application
摘要： To study the effect of Thiazole (as a heterocycle with donation group) in DSSCs, sample A was made without heterocycle, samples B and C contain one Thiazole and various donor group but sample D had two Thiazole group. Moreover, the effects of a double Azo group, and increasing the length of π-conjugation by reducing band gap trough heterocycle rings (donor-donor-π-acceptor system) and Nitro anchoring group were investigated. Nitro groups disappeared in IR at about 1340 and 1598 cm-1 which indicates that dyes successfully connected on TiO2. UV-vis and DRS analysis was studied in visible region that showed Red-shifts for the samples. The HOMO values obtained from the CV tests were calculated between -5.03 to 5.13 eV. The results show that D sample was better than others, showing a 0.5 V increase in its open-circuit voltage in the IV analysis. From the Electrochemical impedance spectroscopy (EIS), Rct value for D cell was measured to be 73.35 KΩ, which is bigger than the other samples, and in line with I-V analysis results.
关键词： DSSC,Nitro anchoring group,Para-azo dyes,Solar cell application
更新于2025-09-11 14:15:04
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Highly cooperative fluorescence switching of self-assembled squaraine dye at tunable threshold temperatures using thermosensitive nanovesicles for optical sensing and imaging
摘要： Thermosensitive fluorescent dyes can convert thermal signals into optical signals as a molecular nanoprobe. These nanoprobes are playing an increasingly important part in optical temperature sensing and imaging at the nano- and microscale. However, the ability of a fluorescent dye itself has sensitivity and accuracy limitations. Here we present a molecular strategy based on self-assembly to overcome such limitations. We found that thermosensitive nanovesicles composed of lipids and a unique fluorescent dye exhibit fluorescence switching characteristics at a threshold temperature. The switch is rapid and reversible and has a high signal to background ratio (>60), and is also highly sensitive to temperature (10–22%/°C) around the threshold value. Furthermore, the threshold temperature at which fluorescence switching is induced, can be tuned according to the phase transition temperature of the lipid bilayer membrane forming the nanovesicles. Spectroscopic analysis indicated that the fluorescence switching is induced by the aggregation-caused quenching and disaggregation-induced emission of the fluorescent dye in a cooperative response to the thermotropic phase transition of the membrane. This mechanism presents a useful approach for chemical and material design to develop fluorescent nanomaterials with superior fluorescence sensitivity to thermal signals for optical temperature sensing and imaging at the nano- and microscales.
关键词： fluorescence switching,optical sensing,nanovesicles,thermosensitive fluorescent dyes,imaging
更新于2025-09-11 14:15:04
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Controlled aggregation of amphiphilic aggregation‐induced emission polycation and superparamagnetic iron oxide nanoparticles as fluorescence/magnetic resonance imaging probes
摘要： Fluorescence/magnetic resonance (MR) dual-mode imaging, which combines the excellent single-cell sensitivity of ?uorescence imaging and the high spatial resolution of MR imaging, has been applied to different biomedical applications. However, the aggregation-caused quenching characteristic of most ?uorescence molecules often put limits in their applications. Herein, a ?uorescence/MR dual-mode imaging probe [polyethylene glycol-polyethylenimine-tetraphenylethene (PEG-PEI-TPE)/superparamagnetic iron oxide (SPIO)] with aggregation-induced emission characteristic is prepared by coupling poly(acrylic acid)-coated SPIO with PEG-PEI-TPE. The ?uorescence intensity and lifetime of PEG-PEI-TPE/SPIO is higher than PEG-PEI-TPE especially at lower polymer concentrations (≤0.2 mg mL?1). Moreover, the ?uorescence intensity of PEG-PEI-TPE/SPIO gradually increased along with the decline of the pH from 9.0 to 4.0, which is bene?cial for studying intracellular organelles. The T2 relaxivity of PEG-PEI-TPE/SPIO is 212.3 Fe mM?1 s?1 under a 3.0 T MR scanner. Cell labeling experiment shows that PEG-PEI-TPE/SPIO can effectively label RAW 264.7 and Hela cells, and labeled cells are visible under both ?uorescence and clinical MR examinations.
关键词： composites,drug delivery systems,dyes/pigments,biomedical applications,self-assembly
更新于2025-09-11 14:15:04
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Electrospinning a Dye-Sensitized Solar Cell
摘要： Dye-sensitized solar cells (DSSCs) offer new possibilities to harvest solar energy by using non-toxic inexpensive materials. Since they can generally be produced on flexible substrates, several research groups investigated possibilities to integrate DSSCs in textile fabrics, either by coating full fabrics with the DSSC layer structure or by producing fiber-shaped DSSCs which were afterwards integrated into a textile fabric. Here we show a new approach, electrospinning all solid layers of the DSSC. We report on electrospinning the counter electrode with a graphite catalyst followed by a thin nonconductive barrier layer and preparing the front electrode by electrospinning semiconducting TiO2 from a polymer solution dyed with natural dyes. Both electrodes were coated with a conductive polymer before the system was finally filled with a fluid electrolyte. While the efficiency is lower than for glass-based cells, possible problems such as short-circuits—which often occur in fiber-based DSSCs—did not occur in this proof-of-concept. Since graphite particles did not fully cover the counter electrode in this first study, and the typical bathochromic shift indicating adsorption of dye molecules on the TiO2 layer was not observed, several ways are open to increase the efficiency in forthcoming studies.
关键词： electrospinning,environmentally friendly,graphite,nanofibers,natural dyes,dye-sensitized solar cell (DSSC)
更新于2025-09-11 14:15:04
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Natural dyes extracted from leaves, fruits, and roots of <i>Piper Betel, Adonidia Merrillii</i> and <i>Morinda Citrifolia</i> as photosynthesizers for dye sensitized solar cells
摘要： In this study, the fabrication of dye sensitized solar cell (DSSCs) using the leaves of Piper Betel (PB), fruits of Adonidia Merrillii (AM) and roots of Morinda Citrifolia (MC) and combination of these three dyes (PB/AM/MC) had been conducted. Fabrication of the DSSCs was conducted using layered system, which involved sandwiching of a working electrode (TiO2 semiconductor) and counter electrode (platinum paste) The chemical and electrochemical characteristic of natural dye extracts were determined using pH meter, Fourier transform infrared (FT-IR) spectroscopy and ultra violet (UV-Vis) spectroscopy. From the study, it was observed that PB dyes showed the highest efficiencies (0.0712 %) followed by the combination dyes (0.0065 %) while AM and MC dyes showed the lowest efficiency (1.0x10-9 % and 0% respectively.
关键词： Morinda Citrifolia,dye sensitized solar cells,Piper Betel,natural dyes,Adonidia Merrillii
更新于2025-09-11 14:15:04