الفهرس 
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Abstract
The investigations of the structural, the electrical transport and the optical properties of FeTPPCl thin films have been investigated in order to obtain the information needed for solar cell optimization and fabrication; and the main conclusions that can be drawn from this thesis can be summarized as follows:
The thermogravic analysis (TGA) and (DTA) curves of FeTPPCl in powder form taken at a heating rate of 10 OC/min reveal that the FeTPPCl has a thermal stability up to approximately 643 K. This analysis indicates that the compound could be used in its solid form for any application up to 643 K.
Structural investigation using X-ray powder diffractograms confirmed that the powder of FeTPPCl has a tetragonal form with lattice constants of a = 13.53 ˚A and c = 9.82 ˚A, whereas the as-deposited and annealed films were amorphous like structure.
The scanning electron microscope, SEM, of the as-deposited FeTPPCl thin film shows uniform formation of the film with island shape (90 nm). After annealing at 523 K for one hour nucleation and growth of the particles can play roles in the morphologies with a significant different particles or grains (250 nm).
The infrared absorption spectra of the powder, the as-deposited and annealed films revealed that the main chemical composition of FeTPPCl has been preserved by thermal evaporation technique.
Absorption spectra of the films showed B, N and C absorption bands in the UV region followed by a Q-band in the visible region. The electronic orbital transitions are assigned as the excitations from the two highest occupied π molecular orbital (HOMOs) into the two lowest unoccupied π* molecular orbitals (LUMOs). The wide absorption range spectrum of FeTPPCl in UV-VIS region indicates that FeTPPCl is suitable for the photovoltaic applications.
The optical constants were characterized using spectrophotometric measurement of transmittance and reflectance at normal incidence of light in the wavelength range 190–2500 nm. By studying the optical absorption properties near the band gap, it is concluded that the FeTPPCl is very similar to amorphous inorganic semiconductors in terms of optical properties. The optical properties of FeTPPCl thin films near the fundamental absorption edge can be interpreted by considering the existence of three types of optical transitions. The mean value of the first transition is the onset optical gap, = 1.53 eV , or excitonic gap and the mean value of last one is the fundamental energy gap, = 2.42 eV. Between them there are one or two transitions corresponding to the trap transitions. It was found that the values of and decrease by increasing the annealing temperature from 298 to 523 K. Also it was found that the X-ray irradiation (20 kGy) has an effect on the excitonic and impurities levels while no effect was observed on the fundamental gap. On the other hand, it was found that the refractive index of the as-deposited film decreases by X-ray irradiation and by increasing the annealing temperature from 298 to 523 K.
The temperature dependence of electrical conductivity in FeTPPCl films indicate that the conduction is through a thermally activated process having three conduction mechanisms. A variable range hopping model, a small polaron model and a simple Arrhenius law (band to band transitions) have been used to explain the conduction mechanism for FeTPPCl films.
Dark current density voltage measurements on Au/FeTPPCl/ITO device show characteristics of typical Schottky-barrier devices. The rectifying behaviour of the device is explained using thermionic emission theory, and the basic diode parameters are determined.
The electrical conductivity and dielectric properties of bulk FeTPPCl has been investigated in the frequency range from 40 Hz to 5MHz and in the temperature range 298–373 K. The frequency dependence of σ(ω, T) follows the Jonscher’s universal dynamic law. The correlated barrier hopping (CBH) model has been applied to the interpretation of the a.c. electrical conductivity. The d.c. conductivity was explained according to the VRH mechanism. No peaks were observed in the dielectric loss, but by using dielectric modulus, peaks can be observed in the imaginary part of the dielectric modulus. M’’ peaks shows an Arrhenius behaviour. The activation energy from the dc conductivity and the relaxation time are quite similar suggesting a hopping mechanism for FeTPPCl.
Hybrid heterojunction cell based on thermally evaporated FeTPPCl as the organic semiconductor and p-Si wafer as the inorganic semiconductor have been investigated. This device showed rectification behaviour like diode. I-V characteristics demonstrated a rectification behavior of p-p isotype heterojunction. Analytical approaches involving the thermionic emission and SCLC current were used to explain the I-V behaviour in the forward bias. The basic diode parameters such as the ideality factor, series resistance and the barrier height were extracted from the I-V measurement of Au/FeTPPCl/p-Si/Al rectifying contacts. The ideality factors were seen to increase and barrier heights decrease by decreasing temperature. These observations have been ascribed to barrier inhomogeneities at the metal semiconductor interface. The investigation of C-V measurements at 1 MHz points out that the junction is of abrupt nature with diffusion potential value of 0.6 eV. The dominant operating mechanism in the reverse bias is generation recombination of carriers, which is a thermally activated process. A short –circuit current of 2.8 mA, an open –circuit voltage of 0.475 V and a fill factor of 32 % were extracted from.(I-V) characteristics under illumination of ≈ 80 mW/cm2. The obtained power conversion efficiency has the value of 5.63 %.