Synthesis And Properties Investigation Of Narrow Band-gap Conjugated Polymers Based On Diketopyrrolopyrrole

Solar energy has become one of the important ways to tackle the energy shortage problems, due to its advantages of clean, pollution-free and renewable. Solar cells are devices that convert solar energy into electrical energy. They can be divided into two different categories:organic solar cells and inorganic solar cells. Inorganic solar cells have demonstrated a power conversion efficiency (PCE) of20%. But there are still many drawbacks such as high manufacturing costs and unwieldy fabrication processes. Compared to inorganic solar cells, more promising organic solar cells have attracted considerable attention owing to their advantages of flexible, low cost and light weight. Poly (3-hexyl thiophene)(P3HT) obtained much attention, oweing to its high PCE of5%. They absorbed light less than650nm, while most of solar energy distributes on light within600-800nm. The most powerful strategy to narrow the band-gap for a broader coverage of the solar spectrum is to form a D-A structure, which copolymerizes electron-rich donor (D) with electron-poor acceptor (A). The selection of acceptor is the key to control band-gap and extend absorption. The diketopyrrolopyrrole (DPP) with being coplanarity and strong electron withdrawing, has attracted much attention.This dissertation covers the major achievements in the field over the past few years and the application in ploymer solar cells. Seven copolymers based on DPP, P1, P2, P3, P4, P5, P6and P7, using fluorene, carbazole and benzodithiophene as electron-withdrawing donor in polymer P1-P4, P5-P6and P7respectively, were designed and synthesized. The structures of these polymers were established by FT-IR and1H NMR. The thermal stability, optical property and electrochemical property of these polymers were investigated by TGA, UV-Vis, PL and CV.