Synthesis And Photoelectric Properties Of Polyfluorene Copolymers Bearing Thiophene And Porphyrin

Polymer solar cells were of interest for future applications in solar cells, compared with inorganic solar cells. Polymer materials were attractive for photovoltaics primarily through the low cost, ease to process and large area flexible devices of them. In this dissertation, on the basis of many literatures in the world were refered by the numbers, the development of principle and devices of organic and polymer solar cells and their materials were reviewed. The main defects of polymers solar cells to their application were narrow spectral coverage, poor mobility of charge carriers and instability of polymer materials, ect. So Four soluble novel polyfluorene copolymers bearing porphyrin and thiophene units with different proportion were synthesized, and their photoelectric properties were also studied.The research results indicated that UV-vis absorption spectra of polyfluorene copolymers had strong absorption over 600 nm spectral range and nearly cover 400~700 nm visible region. These copolymers possessed satisfactory thermal stability. Four copolymers showed good thermal stability with the onset decomposition of 398℃～429℃, and The glass transition temperatures of polyfluorene copolymers were 117℃～152℃. These polyfluorene copolymers had much higher glass transition temperatures in comparison to poly (9, 9-dialkylfluorene) (about 50℃). The band gaps of copolymers calculated according to cyclic voltammetry (CV) were between 1.96 and 2.03 eV. Polymer:TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide, via hydrolysis in air overnight. The photoluminescence at 380~800 nm of the 20% volume fraction Ti(OC3H7)4 blend film of PT-TPP20 (5 mg/mL):Ti(OC3H7)4 (80μL/mL) decreased compared to that of a pristine copolymer film, and PL was significantly quenched in the 50% volume fraction Ti(OC3H7)4 blend film, indicating that an efficient photoinduced charge transfer and separation between copolymer and TiO2 occured. The research results indicated that they were a kind potential polymer solar cell materials.