ABSTRACT
In this work, we investigated the impact of the concentration on the spectral and amplified spontaneous emission spectra (ASE) of a conducting polymer of poly(2,5-di(3,7-dimethyloctyloxy) cyanoterephthalylidene) (PDDCP) in tetrahydrofuran (THF). The findings demonstrate that the absorption spectra exhibited two peaks at 330 and 445 nm across the concentration range (1-100 µg/mL). Irrespective of the optical density, altering the concentrations did not affect the absorption spectrum. Also, the analysis indicated that the polymer did not agglomerate in the ground state for any of the concentrations mentioned. However, changes in the polymer had a substantial effect on its photoluminescence spectrum (PL), likely due to the formation of exciplexes and excimers. Also, the energy band gap also varied as a function of concentration. At a certain concentration (25 µg/mL) and pump pulse energy (3 mJ), PDDCP produced a superradiant ASE peak at 565 nm with a remarkably narrow full width at half maximum (FWHM). These findings can provide insight into the optical characteristics of PDDCP, which may have potential applications in the fabrication of tunable solid-state laser rods, Schottky diodes, and solar cell applications.
Subject(s)
Lasers , PolymersABSTRACT
In this research, nanocomposite solid polymer electrolytes (NCSPEs) comprising methylcellulose/pectin (MC/PC) blend as host polymer, ammonium chloride (NH4Cl) as an ion source, and zinc oxide nanoparticles (ZnO NPs) as nanofillers were synthesized via a solution cast methodology. Techniques such as Fourier transform infrared (FTIR), electrical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) were employed to characterize the electrolyte. FTIR confirmed that the polymers, NH4Cl salt, and ZnO nanofiller interact with one another appreciably. EIS demonstrated the feasibility of achieving a conductivity of 3.13 × 10-4 Scm-1 for the optimum electrolyte at room temperature. Using the dielectric formalism technique, the dielectric properties, energy modulus, and relaxation time of NH4Cl in MC/PC/NH4Cl and MC/PC/NH4Cl/ZnO systems were determined. The contribution of chain dynamics and ion mobility was acknowledged by the presence of a peak in the imaginary portion of the modulus study. The LSV measurement yielded 4.55 V for the comparatively highest conductivity NCSPE.
ABSTRACT
Despite many dedicated efforts, the fabrication of high-quality ZnO-incorporated Zinc@Silicon (Zn@Si) core-shell quantum dots (ZnSiQDs) with customized properties remains challenging. In this study, we report a new record for the brightness enhancement of ZnSiQDs prepared via a unified top-down and bottom-up strategy. The top-down approach was used to produce ZnSiQDs with uniform sizes and shapes, followed by the bottom-up method for their re-growth. The influence of various NH4OH contents (15 to 25 µL) on the morphology and optical characteristics of ZnSiQDs was investigated. The ZnSiQDs were obtained from the electrochemically etched porous Si (PSi) with Zn inclusion (ZnPSi), followed by the electropolishing and sonication in acetone. EFTEM micrographs of the samples prepared without and with NH4OH revealed the existence of spherical ZnSiQDs with a mean diameter of 1.22 to 7.4 nm, respectively. The emission spectra of the ZnSiQDs (excited by 365 nm) exhibited bright blue, green, orange-yellow, and red luminescence, indicating the uniform morphology related to the strong quantum confinement ZnSiQDs. In addition, the absorption and emission of the ZnSiQDs prepared with NH4OH were enhanced by 198.8% and 132.6%, respectively. The bandgap of the ZnSiQDs conditioned without and with NH4OH was approximately 3.6 and 2.3 eV, respectively.
ABSTRACT
In this study, we had investigated the amplified spontaneous emission (ASE) characteristics of CdSe/ZnS quantum dot (QDs) in a colloidal liquid. A third harmonic of Nd:YAG laser (355 nm) was used to produce laser-induced fluorescence (LIF) at 605 nm with a spectral width of 0 nm [full width at half maximum (FWHM)]. When the pump power and focusing were carefully optimized, an ASE at 610 nm with a spectral width of Δλ = 8 nm (FWHM) could be obtained. The beam was directional with a divergence of 10 milli radians (mrad); but the conversion efficiency was about 0.05%.
ABSTRACT
The spectral properties of CdSe/ZnS core-shell quantum dots (QDs) of 3 nm size have been studied under different organic solvents, concentrations and temperatures. Our results showed that the absorption spectra of CdSe/ZnS in benzene have two humps; one around 420 nm and another at 525 nm, with a steady increase in absorption along UV region, and the absorption spectral profile under a wide range of concentrations did not change. On the other hand, the photoluminescence (PL) spectra of CdSe/ZnS in benzene showed two bands one around 375 nm and the other around 550 nm. It could be seen that the band at 375 nm is due to the interaction between the shell (ZnS) with the solvent species in high excited state, and the band at 550 nm is due to core alone (CdSe).
Subject(s)
Cadmium Compounds/chemistry , Luminescence , Quantum Dots/chemistry , Selenium Compounds/chemistry , Sulfides/chemistry , Zinc Compounds/chemistry , Absorption , Benzene/chemistry , Solutions , Solvents/chemistry , Spectrum AnalysisABSTRACT
In this report the dual amplified spontaneous emission (ASE) characteristics of coumarin 138 (C(138)) had been studied, under different solvent environments. The results obtained were compared with coumarin 461 (C(461)) and coumarin 450 (C(450)), which have closely related structure. The results showed that all these dyes could produce ASE from superexciplex - a new molecular species - formed only under high inversion densities, obtainable by pulsed laser excitation. We have strong indication that a superexciplex with TICT conformation is capable of producing strong ASE.