Synthesis and properties of dithieno[3,2-b;2′,3'-d]thiophene (DTT) based molecules for OLED applications

Organic electronics has been the focus of growing number of the researchers particularly in the fields of physics and chemistry for more than 50 years. The main attraction of this field comes from the ability to modify the chemical structure of the organic compounds in a way that the properties of the materials could directly be affected. Until the mid-1980s, their stability and performance fell short of those devices based on materials such as silicon or gallium arsenide. This situation was changed since then with the demonstration of a low voltage and efficient thin film light emitting diode, which opened the door of the possibility of using organic thin films for a new generation of optoelectronics devices. It has now proven that organic thin films are useful in a number of applications. Among them, organic light emitting diodes (OLED) is the most successful one, which is used now in color displays. Organic thin film transistors and low cost and efficient organic solar cells are not far behind OLEDs. Moreover, devices such as organic lasers and memories might be seen eventually. In general, two groups of organic materials, small molecules and polymers, are used in electronic and optoelectronic devices. Understanding of their electronic structure is the key to the design of high performance optical and electronic organic devices, and some important tunings in structure or composition of an organic material can markedly alter its bulk properties. Currently, modification of the molecular structure of the conjugated materials to tune their optoelectronic properties is a challenging topic. Thiophene-based organic materials are among the most promising compounds with tuneable functional properties by proper molecular engineering. For example, thiophenes and their oligomers and polymers are not proper materials for applications in light emitting devices as they have low electron affinities and low solid-state photoluminescence efficiencies. On the other hand, converting oligothiophenes into the corresponding oligothiophene-S,S-dioxides has been shown to be useful for increasing both thin film photoluminescence efficiencies and molecular energy levels. The use of boron to alter the properties of organic electronic and optoelectronic materials has started recently and given interesting results. The reason for that is the presence of empty pz orbital of boron which behaves as strong electron withdrawing atom when it makes three bonds. It delocalizes electrons strongly when integrated to "" systems. In organic material chemistry, conjugated organoborane polymers are now considered as new class of organic materials with their widespread applications in electronics, optoelectronics and sensors. The method developed by our group for the syntheses of ditihenothiophene (DTT) and thienothiophene (TT) having aromatic groups is among the best methods available in the literature. DTTs and TTs are the heterocyclic rings, formed by fused three and two thiophene rings, respectively. In this work, polymers of DTTs, DTT-S,S-dioxides and TTs, prepared by our methods, consisting of boron atoms will be prepared. Cyclic voltammetry (CV), capacitor, ultra-viole (UV), ultra-violet-cyclic voltammetry (CV-UV), sensor and fluorescent properties of the materials will be studied to understand their sensor, electronics and optoelectronics properties. The aim of this study is to enhance the use of boron in new developing organoborane material chemistry and to develop new organic electronics, optoelectronics and sensor materials as our country is rich in boron element.