Enhanced photovoltaic performances of panchromatic EDOT-containing dye by introducing bulky dialkylfluorene units in donor moiety

• A novel donor-π-acceptor (D-π-A) dye having the bulky group has been synthesized.
• The introduction of bulky substituent improved the electron injection efficiency.
• The bulky substituent suppressed the dark current from TiO2 to the electrolyte.

A novel panchromatic donor-π-acceptor (D-π-A) dye composed of oligothiophene having 3,4-ethylenedioxythiophene (EDOT) as a π-linker and the bulky group on the triarylamine donor unit has been synthesized, and its photovoltaic performances were compared with those of dye without bulky group. It was found that the introduction of bulky substituent at the donor unit improved the electron injection efficiency from dye to TiO2 electrode, leading to the enhancement of the short-circuit current (Jsc). Also, the bulky substituent suppressed the dark current from TiO2 to the redox electrolyte, which improved the open-circuit voltage (Voc).

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