“…The absorbance profile presents a broad peak at 511 nm. The optical bandgap was determined using the extrapolation of the absorbance plot according to the relation 11 Fig. 4 Absorbance versus wavelength for the sprayed MEH-PPV polymer thin layer.…”
An Al/p-Si/poly[2-methoxy-5-(2-ethylhexoxy)-p-phenylenevinylene] (MEH-PPV)/Ag organic heterojunction has been prepared using homemade ultrasonic spray pyrolysis (USP) equipment for deposition of the organic thin film and physical vapor deposition (PVD) for the metallic contacts. The organic layer produced on glass was analyzed by optical and morphological methods. The bandgap of the organic thin film was found to be $ 2.03 eV with a thickness of around 140 nm, using ultraviolet-visible (UV-Vis) and scanning electron microscopy (SEM) characterization, respectively. The amorphous nature of the MEH-PPV polymer was confirmed by its x-ray diffraction pattern. To determine the electrical parameters, the heterojunction based on MEH-PPV was characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements in the dark at room temperature. The ideality factor and barrier height of the organic heterojunction were found to be 3.6 eV and 0.56 eV to 0.59 eV, respectively, with an average series resistance of 94.39 X, based on the I-V characteristics. The barrier height was also calculated based on the capacitance-voltage measurements, yielding slightly different results due to the applied frequencies of 10 kHz (/ B ¼ 0:50) and 1 MHz ð/ B ¼ 0:74Þ, respectively.
“…The absorbance profile presents a broad peak at 511 nm. The optical bandgap was determined using the extrapolation of the absorbance plot according to the relation 11 Fig. 4 Absorbance versus wavelength for the sprayed MEH-PPV polymer thin layer.…”
An Al/p-Si/poly[2-methoxy-5-(2-ethylhexoxy)-p-phenylenevinylene] (MEH-PPV)/Ag organic heterojunction has been prepared using homemade ultrasonic spray pyrolysis (USP) equipment for deposition of the organic thin film and physical vapor deposition (PVD) for the metallic contacts. The organic layer produced on glass was analyzed by optical and morphological methods. The bandgap of the organic thin film was found to be $ 2.03 eV with a thickness of around 140 nm, using ultraviolet-visible (UV-Vis) and scanning electron microscopy (SEM) characterization, respectively. The amorphous nature of the MEH-PPV polymer was confirmed by its x-ray diffraction pattern. To determine the electrical parameters, the heterojunction based on MEH-PPV was characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements in the dark at room temperature. The ideality factor and barrier height of the organic heterojunction were found to be 3.6 eV and 0.56 eV to 0.59 eV, respectively, with an average series resistance of 94.39 X, based on the I-V characteristics. The barrier height was also calculated based on the capacitance-voltage measurements, yielding slightly different results due to the applied frequencies of 10 kHz (/ B ¼ 0:50) and 1 MHz ð/ B ¼ 0:74Þ, respectively.
“…In the case of OxFl spectra, an additional peak (at around 309 nm) with slow intensity appeared, which originates from fluorene unit. 31 The first absorption maximum was attributed to the π – π * transitions of the aromatic chromophore (phenylene units), while the second maximum is due to n – π * and π – π * transitions from all conjugated molecules (i.e. C=N bonds, fluorene, and 1,3,4-oxadiazole units).…”
New aromatic polyazomethines were synthesized by polycondensation reaction of a diamine containing 1,3,4-oxadiazole ring, namely, 4,4′-diamino-4″-[2-(4-phenoxy)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole)]triphenylmethane, with terephthalic aldehyde or bis(4-formylphenoxyphenyl)fluorene, by using N-methyl-2-pyrrolidinone (NMP) as solvent. The polymers were easily soluble in polar solvents, such as NMP, N, N-dimethylacetamide, or chloroform, and showed high thermal stability with the initial decomposition temperature above 415°C and the temperature of 10% weight loss in the range of 450–460°C. They exhibited high char yield at 800°C in the range of 52–56%. Optical properties were studied by absorption and photoluminescence spectra. In solution, the polymers presented two absorption maxima in the ranges 273–278 and 330–346 nm and emitted violet-blue light in the range of 413–468 nm, depending on the solvent polarity. The Stokes shift and emission quantum yield values depend on the polymer structure and solvent polarity. The emission intensity in NMP solution was enhanced upon increasing the HCl concentration, while the absorption spectral profile was slightly influenced.
“…In contrast, the Alq 3 embedded into PVA thin film shows similar FTIR spectrum as PVA thin film except for the appearance of three peaks at 2176, 1580, and 750 cm −1 . The 2176, 1580, and 750 cm −1 peaks correspond to Al-O-H, C = N, and Al-N modes for Alq 3 chemical bonding [46][47][48], respectively. The SEM image of Alq 3 :PVA thin film was also obtained as shown in Fig.…”
Section: Characterisation Of Alq Thin Film Samentioning
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