الفهرس 
Theoritical Background and Literature SurveyOnly 14 pages are availabe for public view
 |  | from | 238 |  |  |
| | | from | 238 | | |
Abstract
The physical properties of an organic semiconductor material arise from delocalized π electrons, adsorbed species, defect sites and the presence of functional groups. The presence of different substitution groups on the Quinoline ring [e.g. electron withdrawing group, electron donating group and metal complex] has great influence on structural, thermal, optical, electrical and dielectrical properties of quinoline.
In this thesis, an investigation is performed on the effect of two different donor substitution groups, namely Chlorophenyl and Phenoxyphenyl, on structural, thermal, optical, electrical and dielectrical properties of 4H-pyrano [3, 2-c] quinoline (HPQ) thin films; as well as the role of some experimental conditions namely film thickness and annealing temperatures on the mentioned properties has been investigated . For the Chlorophenyl, the carbon–chlorine bond is enriched with an electron by inductive effect. So the Chlorophenyl is a donor substitution group with respect to HPQ compound. In the Phenoxyphenyl, the oxygen as a substitution atom has a lone pair of electrons that are shared with the aromatic ring. So the Phenoxyphenyl is also a donor substitution group with respect to HPQ compound. But, Phenoxyphenyl is a stronger donor substitution group than Chlorophenyl. The thesis is divided into seven chapters; a summary of their contents is as follows:
In Chapter 1; we are concerned with theoretical aspect and methods which are applied in explaining the experimental data; structural, optical and electrical transport properties of Ph-HPQ and Ch-HPQ thin films. Also, it contains the basics of optoelectronic applications. A literature survey about quinoline and its derivatives is given.
In Chapter 2; processing technologies of producing HPQ thin films used in this work are reviewed.
Chapter 3 deals with the structure of Ph-HPQ and Ch-HPQ thin films. The compounds are polycrystalline in as- synthesized powder form; they became nanocrystallites dispersed in amorphous matrix upon thermal deposition to form thin films. The obtained results of AFM are in agreement with those obtained by XRD technique. FTIR spectral measurements showed no change in chemical bonds of the compounds after being deposited to form thin films.
In chapter 4; the optical properties have been determined based on spectrophotometer measurements of transmittance and reflectance at nearly normal incidence of light in the spectral range of 200–2500 nm. The absorption parameters; molar extinction coefficient, oscillator strength and electric dipole strength are reported. In addition, oscillator and dispersion energies, the high frequency dielectric constant, lattice dielectric constant and ratio of free charge carriers concentrations to their effective masses are evaluated for the compounds under investigation.
In chapter 5; the thermal annealing effect on the optical properties of Ph-HPQ and Ch-HPQ compounds as thin films are studied.
In chapter 6; AC electrical conductivity and dielectrical properties of Ph-HPQ and Ch-HPQ thin films are determined in the frequency range 0.5 kHz -5 MHz with a variation of temperature in the range 290 - 443K. The AC electrical conduction, in Ph-HPQ and Ch-HPQ, is governed by the correlated barrier hopping (CBH) mechanism. Some parameters such as: barrier height, W, maximum barrier height, WM, the density of the charges, N, and the hopping distance Rω were determined as functions of temperature and frequency.
In chapter 7; The energy band diagrams of Ph -HPQ / p-Si and Ch-HPQ/p-Si devices are illustrated. The electrical properties of Au/ Ph -HPQ / p-Si/Al and Au/ Ch-HPQ / p-Si/Al heterojunction diodes are studied in terms of current–voltage characteristics. The two devices are fabricated with the same specifications. They showed a rectification behavior and photovoltaic properties in dark and under illumination conditions.