The Synthesis And Characterization Of Dithieno[3,2-b:2’,3’-d]Thiophene Based Conjugated Polymers As Photovoltaic Materials

With the development of the society, energy problem is becoming much more urgent. So many people are looking for new energy resources in order to find an energy sustainable development way. As a renewable energy resource, solar energy is non-polluting and cost-effective. It provides a good research direction to researchers for new energy exploitation. In recent years, organic photovoltaics (OPV) based on organic conjugated polymers have received enormous attention. The low band gap polymers consisted of alternating donor-acceptor units become hot study of OPV. The introduction of electron-rich and electron poor building blocks into the polymer backbone is considered to be a more powerful and efficient method to reduce the band gap of polymer. Research on narrow band gap polymers is one the most effective ways to improve the energy conversion efficiency of polymer solar cell (PSC).Polythiophenes are regarded as the most important conjugated polymers used in the field of light-emitting diodes, field-effecttransistors and PSCs. The new D-A type polymers designed in this thesis are synthesized with dithieno[3,2-b:2’,3’-d]thiophene(DTT), diketopyrrolopyrrole(DPP),2,1,3-benzothiadiazole (BT), thieno[3,4-c]pyrrole-4,6-dione (TPD) and thiazolo[5,4-d]thiazole (TTz) units.We have used Suzuki-Miyaura coupling reaction and direct arylation polycondensation to prepare four new low band gap polymers which have good thermal stability, optical property and electrochemical property after characterization with’H NMR, GPC, TG, DSC. UV-vis, CV. The band gaps of these four polymers are1.94eV,1.74eV,1.75eV and1.67eV, respectively.