| Summary: | 碩士 === 中國文化大學 === 化學系應用化學碩士班 === 102 === A series of new pyridomethene-BF2/Phenothiazine-hybrid metal-free organic sensitizers K containing different π-spacers were synthesized and applied in dye-sensitized solar cells (DSSC). The introduction of the pyridomethene-BF2 complex unit in the phenothiazine showed a high molar extinction coefficient which is favorable to the light-harvesting.
Moreover, the incorporated unit of pyridomethene-BF2 complex in dyes K weakens the deprotonation effect in solution and on TiO2 film. Quantum chemical calculations were performed by using the density functional theory (DFT) at the B3LYP/6-31G(d,p) level to investigate the structural properties and density distributions of the dyes. Compared to the typical phenothiazine dyes R, the introduction of the pyridomethene-BF2 complex moieties in the phenothiazine significantly increases the photostability.
The effect of the pyridomethene-BF2 complex in dyes K on the performance of DSSC was investigated systematically. With deoxycholic acid coadsorption, insertion of the thiophene unit between the phenothiazine and pyridomethene-BF2 complex in K3 exhibits the best photovoltaic performance, with a short-circuit current density (Jsc) of 15.43 mA cm-2, an open-circuit voltage (Voc) of 0.69 V, and a fill factor (FF) of 0.62, corresponding to a power-conversion efficiency (η) of 6.58% under AM 1.5G irradiation (100 mW•cm-2) condition. The grated additional alkyl chain on the π-bridge thiophene segment in K3 could further improve the Voc.
Additionally, it was found that the substitution position of n-hexyl chain on the thienyl unit has a crucial effect on the molecular electronic structure as well as photovoltaic performance. The introduction of the phenyl pyridomethene-BF2 complex at the N(10) atom of phenothiazine has a good influence on preventing the molecular π-π aggregation. These results suggest that the DSSC based on pyridomethene-BF2 complex dyes could achieve both high performance and photostability.
|
|---|
