Synthesis of organic energy materials; investigation of their properties and device applications

Abstract

Organic conjugated materials are widely used in material chemistry due to their properties such as flexible, easily designed, functional and adjustable band gaps. In particular, conjugated materials are fabricated in areas that provide energy production and conversion, such as organic light emitting diodes (OLED), solar cells, capacitors etc. Organic material chemistry as a combination of synthetic organic chemistry and applied energy science consists of basic steps of design, synthesis, characterization of polymeric or small molecules, investigation of optical and electronic properties and device applications. Global problems like increasing universal energy problems, climate change and depletion of fossil energy resources in today's world increase the interest in energy and development of energy-based materials. Finding and transforming renewable and sustainable alternative energy sources have become important research topics. Thiophene ring, known as heterocyclic compound, is widely used in organic material chemistry. It is used in many energy and energy-based applications due to its suitable reactivity in terms of electrophilic substitution, electron richness and high thermal stability. Within the scope of the thesis design, synthesis, investigation of photophysical properties and device applications of fused thienothiophene (TT) and dithienothiophene (DTT) structures of thiophene family are discussed. The structures given in this thesis have been developed by modifying TT and DTT units with triphenylamine (TPA), tetraphenylethylene (TPE), benzothiadiazole (BTD), anthracene, biphenyl and single-walled carbon nanotube (SWCNT). Through the scope of the doctoral thesis, 11 articles related with organic light-emitting diode (OLED), organic field-effect transistor (OFET), capacitor, fluorescent, memory device, new generation hybrid materials, electrocatalytic and electrochemistry-themed application areas have been produced. Both polymeric and small molecules with various suitable donor-acceptor models for these themes were developed. Various theories and rules such as HOMO-LUMO band energy, intramolecular charge transfer, solid-state and solution quantum efficiency, luminescence efficiency, cavity mobility, external quantum efficiency, aggregation-induced radiation, fluorescence, capacitive properties are covered in the thesis. In conclusion; within the scope of the thesis, both polymeric and small molecule materials based on conjugated TT and DTT were designed, synthesized and their energy applications were investigated. The aim of the PhD study to make contributions both organic chemistry and applied energy. The outputs obtained from this doctoral thesis showed that TT and DTT materials shed light on the development of new generation materials and sustainable energy applications.