Synthesis, Properties Of The Lactam-or Imide-based Conjugated Polymer

Solution-processable conjugated polymers have attracted tremendous attention in the field of organic thin-film transistors (OTFTs) owing to many advantages such as light weight, low cost, and high flexibility. So far, typical semiconductors for developing high-performance OTFTs have only focused on those lactam- or imide-based units. In this thesis, we designed and synthesized a series of different types of new conjugated polymers based on lactam or imide acceptor units,the thermal stability, photophysical-, electrochemical propertiesand microstructure were also investigated, and study the performance of the polymer applied to the organic thin film transistor.(1) Herein, three new BIBDF-based donor-acceptor (D-A) polymers, containing thieno[3,2-b]thiophene (TT), (E)-2-(2-(thiophen-2-yl)vinyl)thiophene (TVT) and (2-(thiophene-2-yl)alkynyl)thiophene (TAT) as donors, were synthesized by stille cross-coupling. Three BIBDF-based polymers exhibited low LUMO energy levels. The polymer film prepared by Spin coatinghas long range order, lamellar packing and short π-π stacking distances, The OTFT devices based on the three polymers were fabricated, all the three BIBDF based polymers showed good n-type field-effect characteristics under vacuum. After annealing, the electron mobility of the devices was 0.65,0.55, and 0.13 cm2V-1s-1 respectively.(2) In order to improve the electron deficient of the polymer, we introduced two receptor units in the polymer structure and designs lactam- or imide-based acceptor-π-acceptor (A-π-A) type conjugated polymers. Three Copolymers (P1, P2 and P3) based on benzodithio-phenedione and diketopyrrolopyrrole units were synthesized by Suzuki reaction. The DPP-based polymers exhibited appropriate HOMO energy level for holes injected, copolymers exhibited ambipolar transport under vacuum. The optimized copolymer P3 exhibited a balanced hole and electron mobility of 0.022 and 0.028 cm2V-1s-1 respectively.(3) In order to further improve the electron transport properties of semiconductor materials, we introduced two lactam-or imide-based receptor units in the polymer structure. An A-π-A type polymer based on phthalimide and diketopyrrolopyrrole units has been designed and synthesized by Stille cross-coupling reaction, compare with P1, P2 and P3, PDPP-PhT exhibited lower LUMO energy level. After annealing, the polymer film has long range order, lamellar packing and short π-π stacking distances. polymer film has long range order, lamellar packing and short π-π stacking distances, polymer-based OTFTs devices exhibited n-type charge transfer under vacuum and yielded electron mobility as high as 0.52 cm2V-1s-1.