Ahmad Nazib Alias

Optical Characterization of Luminescence Polymer Blends Using Tauc/Davis-Mott Model

The optical and electronic structures of poly (N-carbazole) (PVK) blend with poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) and polyvinylpyrrolidone (PVP) in the same composition were investigated. Polymer coating was carried out using doctor blade technique on a glass substrate. Uv-vis and photoluminescence spectrum revealed that there are significant different results obtained between PVK, PVK:PVP and PVK:PVDF-HFP. The electronic parameters such as absorption edge (Ee), allowed direct bandgap (Ed), allowed indirect bandgap (Ei) and Urbach edge (Eu) were calculated by using Tauc/Davis-Mott Model. The value of Ee and Ed for PVK and PVK:PVDF-HFP almost same but there was significant different value between Eu and Ei.

Study on Dispersion and Characterization of Functionalized MWCNTs Prepared by Wet Oxidation

The MWCNTs was functionalized by refluxing commercial MWCNTs (a-MWCNTs) in concentrated HNO3/H2SO4 (3:1 v/v) at 100°C for 6 hours. The dispersion of a-MWCNTs and functionalized MWCNTs (f-MWCNTs) were observed after 1 hour sonication in ethanol. Both samples were characterized by UV-vis spectroscopy for dispersion behavior. The dried f-MWCNTs and a-MWCNTs were characterized by Raman spectroscopy to estimate the defect level. The morphology of the samples were analyzed by Transmission Electron Microscopy (TEM). The f-MWCNTs was well dispersed in ethanol within 2 weeks of observations period. The colloidal stability of a-MWCNTs was low as it was easily sediment after 24 hours. The UV-vis spectra of f-MWCNTs show maximum absorbance at 250 nm meanwhile no absorbance was observed for a-MWCNTs. Analysis from Raman spectrum shows that the f-MWCNTs have relative intensity of 1.101 which is higher than a-MWCNTs that have relative intensity of 0.935. The image from TEM revealed that the f-MWCNTs have structural defects and the absence of amorphous carbon on sidewall meanwhile the a-MWCNTs indicate otherwise.

Optical properties of hybrid PEDOT-PSS: ZnO thin film

Hybrid PEDOT-PSS: ZnO thin film have been prepared using drop casting method. The optical properties such as refractive index (n), extinction coefficient (k), reflectivity (R), optical dielectric loss, optical conductivity (σ), dispersion energy (Ed), oscillator energy (E0) and optical energy band gap (Eg) have been calculated in this paper. The determinations of optical constants have been made by applying the single-effective oscillator model proposed by Wemple and Didomenico Jr. We found that the reflectance is decreasing as the composition of ZnO increase. The refractive index of film also show significantly changes with the volume composition of ZnO. As the composition of ZnO increase, the refractive index shows the normal dispersion behavior. The extinction coefficient is decreasing with the increasing of wavelength, but as the wavelength increase from 400 nm until 700 nm, the extinction coefficient is also increasing. Both the real and imaginary part of the dielectric constant decrease as the photon energy increase. The oscillator energy Eo, dispersion energy Ed, optical band energy Eg were determined by using Wemple DiDomenico single-effective-oscillator model. It is shown that Eo is increasing as the composition of ZnO increase, Ed is decreasing as the composition of ZnO increase and Eg is increasing as the composition of ZnO increase. It is shown that the compositions of ZnO influence the optical properties of hybrid PEDOT-PSS: ZnO thin film.

Excitation and Emission Properties of Poly(N-Carbazole)/Poly(vinylpyrrolidone) Blends Characterized by Fluorescence Spectroscopy

We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blend with different compositions of polyvinylpyrrolidone (PVP). Doctor blade technique was used to coat the blended polymer on a quartz substrate. The influences of polymer composition to the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation, emission and Stokes shift for each samples. The variation of Full Width at Half Maximum (FWHM) for excitation and emission indicate that the variation in composition has affected on the fluorescence properties of the blended thin film polymer system. Fourier Transform Infrared (FTIR) spectroscopy reveals that the discrepancy in the emission and excitation properties of this polymer blending system is due to the discrepancy of infrared absorption peak in the carbazole functional group.

Characterization of poly (N-vinlycarbazole) blending with different composition by using polarized electronic spectroscopy

Polarized absorption and dielectric spectra of blended poly (N-vinlycarbazole) (PVK) with polyvinylpyrrolidone (PVP) in different composition ratiosare investigated. Polymer coating was carried out using doctor blade technique on a quartz substrate. The polarized optical source was produced by using the uv-vis sheet polarizer. The polarized absorption and dielectric spectrum for parallel and perpendicular reveal that there are different significant results obtained between PVK and PVP with various polymer compositions.The polarized optical properties such aspolarization, ρwere calculated.These spectra indicate that the anisotropic properties of each polymer blends is different from each other.

Polarized absorption and dielectric spectra of poly (N-carbazole) blends

Polarized absorption and dielectric spectra of poly (N-carbazole) (PVK) blend with poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) and polyvinylpyrrolidone (PVP) in the same composition ratio were investigated. Polymer coating was carried out using doctor blade technique on a glass substrate. In order to investigate the effect of polarization in polymer blending, we located the uv-vis polarizer before and after the optical excitation source. The polarized absorption and dielectric spectrum for parallel and perpendicular reveal that there are significant different results obtained between PVK, PVK:PVP and PVK:PVDF-HFP. These spectra indicate that the anisotropic properties each polymer blends are different from each other.

Effect of Salt Concentration and Humidity on the Ionic Conductivity of Poly(Vinylidene Fluoride–Hexafluoropropylene) (PVdF-HFP)

Polymer electrolytes consist of poly(vinylidene fluoride –hexafluoropropylene) (PVDF-HFP) and lithium trifluoromethanesulfonate, LiTf (LiCF3SO3) were prepared by dissolving in dimethylformamide (DMF) using solution casting method and further dried in vacuum oven. The conductivity of each sample was investigated using electrochemical impedance spectroscopy (EIS) method. The samples were measured in two different environments viz. in humidity chamber (40% RH; 27°C) and at ambient condition (~60% RH; 27°C). The maximum conductivity obtained for the samples in humidity chamber was 8.05 × 10-5 S/cm with addition of 35 wt% of LiTf. Meanwhile, the highest conducting samples (with addition of 45 wt% of LiTf) exhibited the ambient condition temperature of 1.11 ×10-4 S/cm. Further increased salt concentration from the optimize concentration values has reduced the conductivity of the polymer electrolyte. Dielectric permittivity studies revealed that samples showed the non-Debye behaviors

Optical Characterization of Thiophene Blending with Non-Conjugated Polymer at Different Composition

Thin film conducting polymer thiophene based that is poly(3,4-ethylenedioxythiophene): poly(styrene sulphonic acid) (PEDOT:PSS) blended with Polyaniline (PANi) have been prepared with different composition by using drop casting technique. The optical characterization has been done by analyzing the absorbance spectra in the wavelength 300 to 800 nm. The electronic parameters were calculated by using Tauc/Davis-Mott Model. The results obtained showed that the absorbance, optical energy and Urbach energy were dependence on the ratio of PEDOT: PSS to PANi compositions.

Optical Studies of Poly (N-Carbazole) (PVK) Blending with Polyvinylpyrrolidone (PVP) Using Tauc/Davis-Mott Model

The optical absorption spectra of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) in various compositions are investigated. A doctor blade technique was used to coat the blended polymer on a quartz substrate. The electronic parameters such as absorption edge (Ee), allowed direct band gap (Ed), allowed indirect band gap (Ei), Urbach edge (Eu) and steepness parameter (γ) were calculated using Tauc/Davis-Mott Model. The results reveal that the Ee, Ed and Ei increase with increasing of PVP ratio. There also have variation changing in Urbach energy and steepness parameter.

Refractive Index Dispersion and Optical Dielectric Properties of Poly(N-Carbazole)/Poly(vinylpyrrolidone) Blends

Different compositions of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) were prepared. The optical properties such as infinite frequency refractive index (n∞), average oscillator wavelength (λ0), oscillator strength (So), dispersion energy (Ed), oscillator energy (Eo) and optical dielectric loss have been calculated. The refractive index of polymer blending systems significantly changes with the volume composition of PVP and shows a normal dispersion behavior. Mean while, the values of n∞, Ed and Eo increase with the increase of PVP composition. Both of the real and imaginary part of the dielectric constant decrease as the wavelength increase. Thus, it reveals that the polymer composition has influenced the optical properties of the polymer blending system.