Synthesis And Device Performance Of Novel Organic Optoelectronic Materials

Since the discovery of conducting polyacetylene in the 1970s,increasing interest has been paid to the research of organic optoelectronic materials and devices.Significant progresses have been made in recent years regarding organic optoelectronic devices,especially organic field-effect transistors and organic solar cells.For organic optoelectronic devices,it is important to design and synthesize optoelectronic materials with excellent performance.In this thesis,new optoelectronic materials have been designed and synthesized for organic field effect transistors and organic solar cells.Some main results are obtained as follows:1.In order to solve the problem that the building blocks for efficient small molecule donors are limited to few symmetric units,an asymmetric structure unit was introduced for small molecule donor materials and three novel asymmetric small molecules（IT3T,ITFBT and IT2FBT）were prepared by Stille coupling reaction.The chemical structures and the purity of all new compounds were characterized by NMR,elemental analysis and high resolution mass spectrometry（HRMS）.The optical and electrochemical properties of the molecules were studied by UV-visible absorption and cyclic voltammetry measurement.Subsequently,these small molecules were used as donor materials for the conventional organic solar cells.The results showed that the device based on ITFBT exhibited the best PCE of 4.57%among the three small molecules.The device based on IT2FBT had the highest open circuit voltage of 1.01 V,while the device based on IT3T showed poor performance.Finally,atomic force microscopy and space charge limiting current method were used to investigate these device performance differences.Our results show that the asymmetric indenothiophene can be used as an excellent building block for small molecule donor materials.2.An indenothiophene-based polymer,ITTF was designed and synthesized.The optical and electrochemical properties of the polymer were characterized by UV-visible absorption and cyclic voltammetry.Then the polymer was used as donor material for organic solar cells,and the preliminary device performance was explored.3.The thienoisoindigo monomer was synthesized and polymerized with 4,7-dithiophene-benzothiadiazole and dithiophene to prepare two polymers,TIID-TBT and TIID-TT,respectively.The optical and electrochemical properties of the polymers were studied by UV-visible absorption and cyclic voltammetry measurement.Subsequently,two polymers were used as the organic semiconductor layer to fabricate organic field-effect transistors.The results showed that the polymer TIID-TBT had a decent hole mobility of 6.13×10^-3 cm²V^-1s^-1.