Synthesis Of Novel ?-Conjugated Polymers And Their Application In Organic Field-Effect Transistors

The development of novel ?-conjugated building blocks is very critical for developing high-mobility polymer semiconductors with good comprehensive properties.In this dissertation,we have designed and synthesized three tetrathienoanthracene-based polymer semiconductors and investigated their field-effect transistor properties.At the same time,four ladder-type ?-conjugated polymer semiconductors containing electron-deficient and highly soluble indacenodithiophene-based building blocks?IDTO-2Br and IDTCN-2Br?have been designed and synthesized.We have also carried out preliminary study on the relationship between the structure and properties of the four ?-conjugated polymer semiconductors.The main contexts are as follows:1)Using a two-dimensional ?-extension strategy,we have designed and synthesized three novel ?-conjugated copolymers?PTTB-2T,PTTB-TT,and PTTB-BZ?by incorporating alkyl-substituted tetrathienoanthracene moities.It is found that three copolymers have good thermal properties,good solubility,deep-lying HOMO values,good planarity,and close ?–? stacking distance.Compared with D–D type copolymers?PTTB-2T and PTTB-TT?,D–A type copolymer PTTB-BZ exhibits highest hole mobility of 0.15 cm²V^-1s^-1.The enhanced carrier-transporting ability for PTTB-BZ mainly arises from compact solid-state packing,uniformly fiber-like morphology,and large polycrystalline grain.2)To develop novel solubilizing indacenodithiophene-based derivations,we have designed and synthesized 2-decyltetradecyl-substituted acceptor building blocks?IDTO-Br and IDTCN-2Br?.Four novel D–A type polymer semiconductors?PIDTO-V,PIDTO-2T,PIDTCN-V,and PIDTCN-2T?have been designed and synthesized,in which IDTO-Br or IDTCN-2Br are used as the electron withdrawing units and vinylene or bithiophene are used as the electron donating units.The results indicate that four copolymers obtain good solubility,good thermal properties,and relatively high molecular weights.Absorption spectra indicate that narrow band gaps?1.27 e V for PIDTO-V and 1.30 e V for PIDTO-2T?are demonstrated for the IDTO-based polymers.Electrochemical data show that deep-lying HOMO/LUMO energy levels are demonstrated for all the four copolymers,due to the incorporation of strongly electron-deficient carbonyl or dicyanovinylene groups into the indacenodithiophene backbones.Especially,deep-lying LUMO energy level values ofbelow –4.20 e V are demonstrated for the IDTCN-based polymers.Generally,deep-lying LUMO energy level values are helpful for fabricating air-stable electron-transporting OFET devices.These findings indicate that the four synthesized copolymers have great potential in high-performane OFETs.