Interchain interactions between π-systems have a strong effect on the properties of conjugated organic materials that find application in devices such as light emitting diodes (OLEDs), organic photovoltaics (OPVs), and field effect transistors (FETs). We have prepared covalently-stacked oligo(1,4-phenylene ethynylene)s and oligo(1,4-phenylene vinylene)s to study the influence of chain-chain interactions on the electronic structure of closely packed conjugated units. These serve as models for segments of conjugated materials in thin film devices. Extension of this concept has allowed us to prepare multi-tiered systems that display the influence of pi-stacking. The stacked architectures were prepared by multi-step synthesis of the scaffolds, followed by metal-catalyzed cross coupling reactions (Sonogashira, Heck, Suzuki couplings) to incorporate the conjugated oligomers. The optical and electrochemical properties of these stacked compounds and polymers were compared to their unstacked linear counterparts. These studies provide a platform for the exploration of the nature of charge carriers and excitons in a broad class of materials that have significant potential in addressing challenges in power generation, lighting and electronics.

Polythiophenes have great potential as semiconductors for use in organic field effect transistors and light emitting diodes. Recent research has been focused on the design, synthesis and characterization of fluorinated polythiophenes and oligothiophenes. Various fluoroalkyl side chains have been introduced to induce polymer self-assembly, to control the electronic properties of the conjugated backbone, and to modify the solubility of the polymer in supercritical CO2. This work led to the preparation of poly(3-(perfluorooctyl)thiophene), which is one of only a few examples of n-dopable polythiophenes, and is the first supercritical CO2-soluble conducting polymer. An alternating copolymer consisting of 3-perfluoroakyl and 3-alkylthiophene units has been synthesized. This polymer, with alternating electron-donating and withdrawing substituents, has a high quantum yield for fluorescence in solution relative to the two homopolymers, and strong fluorescence in solid state. Based on the study on its nanocrystals, the unusual photophyiscs may be due to the formation of the supramolecular structure with hexagonal packing. A novel thiophene monomer, 3-(1,1-difluorooctyl)thiophene, was prepared to further tune the electronic structure of polythiophenes by changing the fluorination pattern of side chains, while retaining solubility in organic solvents by virtue of the hydrocarbon side chain. a-Hexyl-w-perfluorohexylsexithiophene was synthesized to make a novel amphiphilic material for use in TFTs. Models for interchain charge transfer in doped conducting polymers were also developed. Stacked and unstacked conjugated oligomers have been synthesized as models for conducting polymers. The bis(radical cation) form and the dication-neutral form of compounds in which conjugated oligomers are held in a stacked arrangement are shown to coexist and in equilibrium with each other. The coexistence of these two forms further suggests that both may serve as charge carriers. Interconversion between these forms by disproportionation mimics a possible mechanism for charge migration in doped conjugated polymers.

Since the discovery of the photovoltaic effect in bulk heterojunction devices¡Mthe considerable publications in PSCs have been reported¡OPSCs based on the concept of bulk heterojunction (BHJ) configuration where active layer comprises of a p-type donor (conjugated polymer) and a n-type acceptor (fullerene derivative) materials¡Mrepresents the most useful strategy to maximize the internal donor-acceptor interface area allowing for efficient charge separation¡OTo further enhance the power conversion efficiency from solar cells made of poly(3-hexylthiophene)/[6,6]-phenyl C61 butyric acid methyl ester (P3HT/PCBM) ¡M a new conducting polymer with optimized band energy levels are demonstrated to be one of the key properties¡OIn this study¡MI synthesized a soluble and strongly visible-light absorbing alternating conducting polymer using Suzuki coupling polymerization method¡OThe UV-Vis absorption spectra of copolymer contains an intramolecular charge transfer (ICT) transition band¡Mwhich leads to absorption extending to near-infrared region and optical band gaps is 1.55 eV¡OThe photo-electron spectroscopy in air(PESA) measurements show that the HOMO level of the polymer is ~5.0eV which is lower than P3HT¡O

In this study, the characteristics of LPD-NiO, and lithium-doped LPD-NiO filmson glass substrate were investigated. In our experiment, we do some measurement about physical, chemical, electrical and optical properties for LPD-NiO and lithium-doped LPD-NiO films and discussed with them. The NiO film thickness was characterized by field emission scanning electron microscopy (FE-SEM), structure was characterized by X-ray diffraction (XRD), chemical properties were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Electrical properties were characterized by four-point probe, and optical properties were characterized by a reflecting spectrograph. The thermal annealing was used to improve the characteristics of LPD-NiO and lithium-doped LPD-NiO films in nitrogen, air and nitrous oxide ambient. For lithium doping, the lithium chloride was used as the doping solution and the electrical characteristics were enhanced. After thermal annealing in air at 400 oC, the resistivity of NiO films is 7.5 ¡Ñ 10-1 ohm-cm and can be lowed to 7.2 ¡Ñ 10-3 ohm-cm with lithium doping.

This thesis studied on the research of how conducting polymer polyaniline can be used in the buffer layer of organic solar cell. There are two methods used.¡]1¡^Using spin-coating to make film of polyaniline solution.¡]2¡^Polymerizing aniline on the substrate directly by electrochemical polymerization. The electrochemical method is separated into cyclic voltammetry and potentiostatic method respectively. The latter method which improved the disadvantage of infractable thick film and low electric conductivity of polyaniline for spin-coating is chosen as the preparation method for polyaniline films. We discuss of the photoelectric characteristics and surface morphologies of polyaniline film and to make a solar cell base on Poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester measured with AM 1.5G 100 mW/cm2 solar light simulation. This research combine above-mentioned results to use potentiostatic method to polymerize polyaniline on the PEDOT¡GPSS into a compound electrode and to replace currently popular ITO positive pole in a organic solar component. The structure is PEDOT¡GPSS/PANI/P3HT¡GPCBM/Al. By electroplating polyaniline, it can enhance the electric conductivity of the film of PEDOT¡GPSS from 1 S/cm to 154 S/cm, furthermore, to reach 1.06% of photoelectric conversion efficiency and creates a new possibility of preparing a flexible organic solar cell.

The Knorr-Paal reaction of 1,4-di(2-thienyl)-1,4-butanedione with aniline to yield 1-phenyl-2,5-di(2-thienyl)-1H-pyrrole (PTP) was performed in the presence of catalytical amounts of p-toluenesulfonic acid (PTSA). Chemical polymerization of the monomer yielded a soluble polymer. Structures of both the monomer and the polymer were investigated by Nuclear Magnetic Resonance (1H and 13C NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. The average molecular weight of the chemically synthesized polymer was determined by Gel Permeation Chromatography (GPC) as Mn = 7.2 x 103 g/mol. The electrochemical oxidative polymerization of PTP was carried out via potentiodynamic electrolysis in the presence of LiClO4, NaClO4 (1:1) being the supporting electrolyte in acetonitrile. Electrochemical copolymerization of PTP with 3,4-ethylenedioxythiophene (EDOT) was carried out in acetonitrile (ACN)/ NaClO4/LiClO4 (0.1M) solvent-electrolyte couple system via potentiodynamic electrolysis. Cyclic voltammetry was used to investigate electrochemical behavior of the monomer and redox reactions of conducting polymers. Conductivities of films of the polymers were measured by four-probe technique. Surface morphologies of the films were investigated by Scanning Electron Microscope (SEM). Electrochromic properties of the conducting polymers were investigated via spectroelectrochemistry, kinetic and colorimetry studies. Spectroelectrochemical analysis of P(PTP) revealed electronic transitions at 413, 600 and 900 nm corresponding to &amp / #960 / -&amp / #960 / * transition, polaron, and bipolaron band formations, respectively. The spectroelectrochemical behavior of the P(PTP-co-EDOT) in comparison to those of the respective homopolymers revealed solid evidence of copolymerization based upon the differences in the spectral signatures. Switching time of the polymers was evaluated by kinetic studies upon measuring the percent transmittance (%T) at the maximum contrast point. As an application, absorption/transmission type electrochromic devices with ITO/homopolymer(copolymer)/gel electrolyte/PEDOT/ITO configuration was constructed, where homopolymer (copolymer) and PEDOT functioned as the anodically and the cathodically coloring layers, respectively. Spectroelectrochemistry, switching ability and open circuit memory of the devices were investigated. The results revealed that these devices have good switching times, reasonable contrasts and optical memories.

Polymerization reaction is carried out by the reaction of 2,4,6 trichlorophenol with sodium hydroxide, in the presence of small amount of water by microwave initiation. Synthesis of polymers were successfully performed under microwave enegy. The use of microwave energy was due to advantages of shorter processing time. The main focus of attention was the 90 to 600 watt microwave energy. Polymerizations were performed with different time intervals by keeping the microwave energy and water content constant / or with different energy levels by keeping the time interval and water content constant / or by varying the amount of water by keeping the time and energy level constant.Beside poly(dichlorophenylene oxide), conducting polymer, ion-radical polymer, crosslinked polymer were also be successfully synthesized and characterized. Characterizations of the products were performed by FTIR, 1H-NMR, 13C-NMR, DSC, TGA and elemental analysis. Molecular weight distribution was measured by PL-GPC 220 Polymer Laboratories Instrument. Conductivity measurements were performed by four probe technique.

Different substituted thiophene and pyrrole monomers namely hexamethylene (bis-3-thiopheneacetamide) (HMTA), N-(4-(3-thienylmethylene)-oxycarbonylphenyl)maleimide (MBThi), 2,4,6-Tris-(4-pyrrol-1-yl-phenoxy)-[1,3,5]triazine (TriaPy), 2,4,6-Tris-(thiophen-3-ylmethoxy)-[1,3,5] triazine (TriaTh), and N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMT) were synthesized. The chemical structures of the monomers were characterized by Nuclear Magnetic Resonance (1H-NMR and 13C-NMR) and Fourier Transform Infrared (FTIR) Spectroscopies. Electrochemical behavior of the monomers in the presence and absence of comonomers were studied by cyclic voltammetry. Subsequently, monomers were homopolymerized and copolymerized via electrochemical methods and the resultant polymers were characterized by FTIR, Scanning Electron Microscopy (SEM) and conductivity measurements. Second part of the study was devoted to investigate one of most interesting property of conducting polymers, the ability to switch reversibly between the two states of different optical properties, &ldquo / electrochromism&rdquo / . In recent years there has been a growing interest in application of conducting polymers in electrochromic devices. Thus, electrochromic properties of the synthesized conducting polymers were investigated by several methods like spectroelectrochemistry, kinetic and colorimetry studies. Spectroelectrochemistry experiments were performed in order to investigate key properties of conjugated polymers such as band gap, maximum absorption wavelength, the intergap states that appear upon doping and evolution of polaron and bipolaron bands. Switching time and optical contrast of the homopolymers and copolymers were evaluated via kinetic studies. Results implied the possible use of these materials in electrochromic devices due to their good electrochromic properties.

2,3-Dihydro-5-(10-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)anthracen-9-yl)thieno [3,4-b][1,4]dioxine (DTAT) was synthesized via linking 3,4-ethylenedioxy thiophene (EDOT) on anthracene by Stille coupling. Homopolymer P(DTAT) was achieved by electrochemical techniques. The polymer, P(DTAT) was electrosynthesized by anodic oxidation of the corresponding monomer in the presence of 0.1 M LiClO4 as the supporting electrolyte in acetonitrile (ACN) solution. Copolymer of DTAT in the presence of EDOT was synthesized via potentiodynamic method in ACN/LiClO4 (0.1 M) solvent-electrolyte couple. Structural characterizations of the sample was carried out via 1H-Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Electrochemical behaviors of the monomer and polymers were determined by Cyclic Voltammetry (CV). Electrochromic and spectroelectrochemical behavior of the polymers were investigated on ITO glass electrode, and their ability of employment in device construction was examined. Spectroelectrochemistry analysis of P(DTAT) revealed an electronic transition at 505 nm corresponding to &amp / #960 / -&amp / #960 / * transition with a band gap of 1.57 eV. In order to investigate electronic structure of the copolymers obtained by different applied potentials, spectroelectrochemistry studies were performed. Electrochromic investigations showed that P(DTAT) switches between yellow and blue while P(DTAT-co-EDOT) was found to be multichromic, switching between claret red neutral state, a gray and a red intermediate state, and a blue oxidized state. Switching time of the polymers was evaluated by a kinetic study upon measuring the percent transmittance (%T) at the maximum contrast point. Dual type polymer electrochromic devices (ECDs) based on P(DTAT-co-EDOT) with poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed. Spectroelectrochemistry and electrochromic switching of the device was studied. They were found to have good switching times and reasonable contrasts.

A novel electrically conducting polymer, poly(2-dodecyl-4,7-di(selenophen-2-yl)benzotriazole) (Poly(SBT)), containing selenophene as a strong donor and benzotriazole as a strong acceptor group was synthesized by electrochemical polymerization. Homopolymerization and copolymerization ( in the presence of 3,4-ethylenedioxythiophene (EDOT) ) was achieved in acetonitrile/ dichloromethane(95/5 v/v) with 0.1M tetrabutylammonium hexafluorophosphate (TBAPF6). The electrochemical and optical properties of homopolymer and copolymer were investigated by Cyclic voltammetry, UV-Vis, near IR Spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that homopolymer can be reversibly reduced and oxidized (both n- and p-doped) between -1.9 V and 1.4 V, at a scan rate of 100 mV/s. Optical contrast was calculated as 32% and 56% with a switching time of 2.4 s and 0.4 s at 511 and 1200 nm respectively. Poly(SBT) exhibits a &amp / #955 / max value of 511nm and a band gap of 1.67eV.