Synthesis And Photovoltaic Properties Of Based On Polythiophene Derivatives With Triphenylamine And Oxadiazole Side Groups And Organic Dyes With Double Electron Donors

In this dissertation, the research progresses of the materials and devices based on polymer solar cells (PSCs) and dye-sensitized solar cells (DSSCs) were summarized systematically. In order to broaden the absorption band, enhance the charge carrier mobility of photoconductive materials, improve the ability of electron donor of organic dyes and retard charge recombination between electrons at the TiO₂ and the oxidized dyes, we have designed and synthesized a series of new conjugated copolymers containing double di(p-tolyl)phenylamine (TPA) and oxadiazole (OXD) side groups and some high molar extinction coefficient organic dyes containing double TPA donors. The structures of the as-synthesized copolymers and dyes were confirmed by 1H-NMR, 13C-NMR, FT-IR and MALDI-TOF. The photophysical, electrochemical and photovoltaic properties of the copolymers and dyes have been investigated by UV-vis spectra, PL spectra, Transient Absorption Spectra and Cyclic Voltammetry. In addition, the photovoltaic performances of solar cells based on the as-synthesized copolymers and dyes were measured. The main results are as follows:1. Three novel conjugated polymers (P1, P2, and P3), comprised of 2,5-dioctyloxy-1,4-phenylenevinylene and terthiophene derivatives with/without TPA and OXD side groups, have been synthesized via the Witting-Horner reaction. The effect of TPA and OXD side groups on the thermal, optical, electrochemical and photovoltaic properties have been investigated. The study results showed that TPA and OXD side groups could broaden absorption band and enhance the charge carrier mobility of copolymers. Photovoltaic cells were fabricated based on the blend of the as-synthesized copolymers and PC61BM in a 1:4 weight ratio. Under the illumination of AM 1.5 100 mW/cm², the power conversion efficiencies (PCE) for P1, P2 and P3 are 0.72, 1.75, and 1.28%, respectively.2. Two novel branchlike organic dyes (D1 and D2) comprising two TPA moieties as the electron donor and cyanoacetic acid moieties as the electron acceptor were designed and synthesized by a series of classic organic reactions such as Witting-Horner reaction, Stille couple reaction, Knoevenagel condensation reaction for DSSCs. For comparison purposes, the simple dye D3, which has no double TPA substitutes as the donor, was also synthesized. We systematically studied the effects of electron donor and with/ without a hexyl chain in theÏ€-spacer on the photophysical, electrochemical properties, and power conversion efficiency. The study results showed that double TPA groups could not only improve molar extinction coefficient of dyes but also retard charge recombination between electrons at the TiO2 and the oxidized dyes, therefore effectively enhacing the PCE of dyes. Among the three dyes studied, a maximum power conversion efficiency of 6.41% was obtained under simulated AM 1.5 G 100 mW/cm² solar irradiation with a DSSC based on D2 dye (J_sc = 11.62 mA/cm², V_oc = 0.73 V, FF = 0.756), indicating its potential application as the metal-free organic dyes for DSSCs.