Synthesis, Properties Of Conjugated Polymers Based On Isoindigo And Its Derivatives

Isoindigo, an isomer of the well-known dye indigo. It began to be reported and attract the attention of people as a building block for donor-acceptor (D-A) conjugated polymers, it is composed of two strong suction lactam group electrons, resultly, the entire molecule is a relatively strong acceptor unit, at the same time with good planarity, local dipole large can effectively enhance the intramolecular and intermolecular interactions, and can be introduced in alkyl chain and improve solubility. In this thesis, we synthesized a series of conjugated polymers based on isoindigo and its derivatives, study on their properties. The main research is as follows:1. A new conjugated polymer with isoindigo unit as acceptor and π-extended di(thienyl)ethylene (DTE) as donor were synthesized by Stille cross-coupling reaction (Chapter 2). Their optical, electrochemical and electrical properties were studied. Since the electron-deficient isoindigo monomer unit is employed as a building block, electron-rich thiophene-based DTE donor units were combined to increase the donor HOMO level and to fabricate new D-A alternating conjugated polymers for TFT applications. The thermally annealed film of PIIDDTE exhibited outstanding hole mobilities of 0.34 cm2 V-1 s-1.2. A bis(2-oxoindolin-3-ylidene)-benzodifuran-dione (BIBDF)-based low band gap polymer (PBIBDF-BT), containing a solubilizing alkyl chain bithiophene unit as a donor, has been synthesized and characterized. The polymer with a deep LUMO-HOMO energy level, a highly ordered lamellar structure and a small π-π stacking distance showed excellent field-effect electron and hole transport. The electron and hole mobilities are as high as 1.08 and 0.30 cm2 V-1 s-1, respectively.3. A new acceptor unit (BTPBF), and its polymer with dithiophene have been synthesized and characterized. The new polymer has the λmax located farthest into the NIR at 1115 run with the optical band-gap as low as 0.71 eV. The polymer also possesses a deep LUMO energy level, a long-range-ordered lamellar structure and a small π-π stacking distance. The polymer displays high electron and hole mobilities up to0.22 and 0.61 cm2V-1s-1.