| dc.description.abstract | Searching for affordable renewable energy is one of the currently important activities due to the global warming issue. Solar energy is one of the most promising renewable energy sources because it is inexhaustible, clean and less pollution. Dye-sensitized solar cells (DSC) which can convert solar energy into electrical energy, is one of the new generation solar cells under extensive studies. Dye molecules are the source for the photocurrent of DSC. They also affect the power conversion efficiency and stability of the corresponding devices. In this thesis, we focus on the synthesis of blue dyes for DSC. Thienoisoindigo unit was used as auxiliary acceptor (Aa) in a Donor-Auxiliary acceptor-π bridge-Acceptor type dye molecules. Triphenylamine, carbazole and fluorene were used as donor for tuning the molecular’s energy gap to obtain TIID-1, TIID-3 and TIID-5 dyes. Triphenylamine has stronger electron-donating ability than the other two donors, therefore TIID-1 has higher HOMO level and smaller band gap than the other two dyes. The absorption maximum of TIID-1, TIID-3 and TIID-5 are at 650, 632 and 608 nm, respectively. The absorption maximum of TIID-1 and TIID-3 falls on the wavelength of 625~740 nm, therefore are green dyes. The absorption maximum of TIID-5 is 590~625 nm, shows blue green color. TIID-6 is the inverted donor and acceptor poitions related to TIID-5, having lower HOMO and LUMO levels compared to TIID-5 with the absorption maximum blue-shifts to 601 nm. Since TIID-6 still has strong absorption at red-light range, therefore is blue green color. The cyanoacrylic acid in TIID-5 was replaced by carboxylic acid to form TIID-11. The absorption maximum of TIID-11 is 606 nm, also shows blue green. When these dyes were used as sensitizers for dye-sensitized solar cells (DSC), the maximum overall conversion efficiency of 3.26 % is achieved by TIID-1 dye. The lower photovoltaic performance of three dyes is due to the LUMO level is too low to inject the electron from the excited dye to TiO2 efficiently. | en_US |