Molecular Engineering of Efficient Organic Sensitizers Containing Diyne-Bridge for Dye-Sensitized Solar Cells

Diyne unit containing organic dyes coded as FSD105 and FSD106 were designed and synthesized to investigate their light harvesting capabilities and the DSSC performances. Through tuning the geometrical structures of dye molecules by introducing an extra ethynylene, FSD105 and FSD106 showed an obviously improved coplanar geometry, and thus the significantly bathochromic shifted absorption spectra, IPCE spectra and larger Γ values, leading to the enhancement of Jsc which guaranteed the highest η (3.82%) for FSD106-based DSSC. In order to avoid the dye aggregation, CHCl3/EtOH was adopted as the sensitizing solvents instead of CHCl3 only or CDCA as coadsorbent was added to reduce the Γ value of FSD106-based DSSC. As a result, the Jsc and the η value increased significantly. Finally, FSD106/CDCA-based DSSC showed the highest η value (4.76%), which is 1.53-fold as the previous reported FSD101-based DSSC (3.12%) by introducing an extra ethynylene to improve the molecular coplanarity.

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