| Summary: | 碩士 === 國立中央大學 === 化學學系 === 106 === A series of new di-anchored organic dyes containing a tetraphenylethylene tethered phenothiazine core (YL) featuring with different π-bridging units (thiophene, 3-hexylthiophene, 4-hexyl-2, 2’-thiophene, cyclopenta[1,2-b:5,4-b']dithiophene) have been synthesized via Stille coupling, Vilsmeier-Haack formylation and Knoevenagel condensation reactions, and used as the sensitizers of dye-sensitized solar cells (DSSCs). Incorporation of a nonplanar TPE entity with propeller-like configuration is beneficial to suppressing π‒π aggregation of the dye molecules. Besides, TPE-induced more compact dye packing on TiO2 surface in collaboration with double anchors are expected to more effectively suppress the dark current of DSSCs.
These new dyes have electronic absorption raging from 300 to 600 nm, with the highest molar coefficient surpassing 70000 M-1cm-1. The HOMO (5.37 to 5.47 eV) and LUMO (3.26 to 3.31) energy levels of the dyes calculated from the electrochemical and photochemical data assure sufficient thermodynamic driving force for electron ejection and regeneration. The light to electricity conversion efficiency of YL dyes ranges from 3.94 to 7.11% under simulated AM 1.5 G illuminations and from 8.64 to 11.45% under 6000 lux. Among them, the YL-2 which a 3-hexylthiophene spacer in the π-conjugated bridgunites between the donor and the acceptor has the best efficiency under 1 sun, reaching 81% of N719-based standard cell.
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