Synthesis And Study On The Photovoltaic Properties Of Conjugated Polymers With 3, 4-ethylenedioxythiophene And Triphenylamine Organic Dyes

In this dissertation, the advances in the materials of conjugated polymers for heterojunction solar cells and organic sensitizers for dye sensitized solar cells(DSSCs) were reviewed briefly. To improve the absorption spectra and carrier mobility of the materials, we designed and synthesized a serious of triphenylamine dyes and conjugated copolymers. The structures of the as-synthesized organic dyes and copolymers were characterized by 1H-NMR, 13C-NMR and FT-IR. The photophysical, electrochemical and photovoltaic properties of the desired products have been investigated. The main studies are as follows:1. Two novel conjugated polymers(P1 and P2), comprised of 2,5-dioctyloxy-1, 4-pheny-lenevinylene and 3, 4-ethylenedioxythiophene units with oxadiazole side groups(TTh-Oxa), have been synthesized via Witting-Horner reaction. For comparison, another poly(p-phenylene vinylene)(PPV) derivative P3 was also synthesized. The effect of TTh-Oxa unit on the optical, electrochemical and photovoltaic properties has been investigated. It is found that P1 and P2 exhibit a broader and stronger absorption than that of P3 for the introduction of TTh-Oxa unit. Photovoltaic cells have been fabricated with the as-synthesized polymers as the donors and PCBM as the acceptor in a 1:4 weight ratio. Under simulated AM 1.5G solar irradiation(100 mW/cm~2), the device based on P1～P3 showed power conversion efficiency of 0.64%, 0.58% and 0.07%, respentively.2. Three donor acceptorπ-conjugated(D-π-A) organic dyes have been designed and synthesized as dye sensitizers for the application in DSSCs. The electron-donating moieties are triphenylamine or di(p-tolyl)phenylamine, and the electron-withdrawing parts are cyanoacrylic acid group, methylthiophene or vinylene methylthiophene are introduced to the molecules and serve as electron spacers. Detailed investigation on the relationship between the dye structure, photophysical and photoelectrochemical properties are studied here. It is found that the vinyl unit, introduced in theπ-conjugated spacer, leads to unfavorable back-electron transfer and decrease of the open-circuit voltage. On the basis of optimized conditions, The dye-sensitized solar cells based on 2-cyano-3-(5-(4-(diphenylamino)phenyl)- 4-methylthiophenyl-2-yl) acrylic acid(TD1) showed the most efficient solar-to-electricity conversion efficiency compared to other dyes, which is the maximumηvalue of 8.27%(Jsc = 15.76 mA/cm~2, Voc = 0.72 V, and FF = 0.73) under simulated AM 1.5G solar irradiation(100 mW/cm~2).