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The present thesis is devoted to investigate the structural, optical and properties as well as photovoltaic application of MnTPPCl thin films deposited by thermal evaporation technique with different thickness under vaccum of about 10-4Pa with a deposition rate 2.5 nm s-1.
The structural properties of MnTPPCl in powder and thin film forms were investigated by X-ray diffraction patterns. X-ray diffraction (XRD) patterns of MnTPPCl indicated that the material in the powder form is polycrystalline with triclinic structure and space group (P1) and lattice constants a=8.638Å, b=5.147Å, c=18.752Å, α=90.76º, β=82.43º,γ=90.10º, Miller indices (hkl)for each diffraction line were calculated. While the X-ray diffraction of the as-deposited film revealed amorphous structure, After the annealing process at 473 K, the XRD pattern of film showed a partially crystalline with peak around (2θ=17.96 º) with preferred orientation along (011) plane. The intensity of the significant peak was increased with increasing of annealing temperature up to 523 K. There patterns show that annealed film at 523K is completely crystalline indicating that the annealing enhances the crystallinity of the films.
The surface morphology of MnTPPCl thin films was studied by using SEM technique. The average particle size increases ranging from 50 nm for the as-deposited films reaches up to 1.954μm for films annealed at 523K.
The infrared absorption spectra of powder, as-deposited and annealed films were examined. A comparison of the Fourier transformation infrared (FT-IR) absorption spectra of powder, the as-deposited and the annealed thin film showed that MnTPPCl has thermal and chemical stability.
The optical properties of thermally evaporated MnTPPCl thin film have been characterized by using Spectrophotometric of transmittance and reflectance in the spectral range of (200-2500 nm). The transmittance and reflection of as-deposited MnTPPCl thin films showed that in the wave length range (200-750) nm the film is absorbing for light waves while in the wave length range (750-2500) nm the film is optically transparent. The annealing process shifts the transmittance edge to higher wave length and reduces the peak intensity of the interference.
Some of the important spectral parameters, namely optical constant (absorption index (k) and refractive index (n)) were calculated for as-deposited and annealed films. The HUMO-LUMO gap was found to be 1.92eV after annealing process the HUM0-LUMO gap was found to decrease.
Some of the optical absorption parameters, namely, the optical absorption coefficient (α), molar extinction coefficient (εmolar), oscillator strength (f) and electric dipole strength (q2) have been also evaluated. We calculated the non-linear absorption coefficient by using linear refractive index.
The normal dispersion of refractive index, n was discussed in terms of single oscillator model of Wemple-Didomenico while the anomalous dispersion (exhibits various peaks) can be explained according to multi-oscillator model. The dispersion parameters oscillator energy Eₒ , dispersion energy Ed, optical dielectric constant at higher frequency,ε_∞, lattice dielectric constant,ε2, and the ratio of free carrier concentration to the effective mass, N/m* were determined. the real part of the dielectric constant,ε1 ,the imaginary part of the dielectric constant ,ε2,the loss factor, tan δ, the real and imaginary parts of optical conductivity (σ1 and σ2), the volume and surface energy loss functions (VELF and SELF) were also estimated.
The spectral behavior of ε1 and σ2 was found to follow the same trend of n (dispersion theory) while, ε2, σ1, tanδ, VELF and SELF was found to follow the behavior of , k, which is related to the variation of absorption coefficient, α, with photon energy(Absorption theory).
The fabricated Hybrid heterojunction cell Au/MnTPPCl/p-Si/Al based on the thermally evaporation MnTPPCl as the organic semiconductor on p-Si wafer as the inorganic semiconductor has been investigated for photovoltaic application.
This device showed rectification behavior like diode. The basic diode parameters such as the ideality factor, barrier height, series resistance and shunt resistance were determined.
A short circuit current of 4.2818×10^(-7)A, an open circuit voltage of 0.5029V and fill factor 0.15 were extracted from (I-V) characteristics under illumination.