Investigation of the photovoltaic performance of dye-sensitized solar cells utilizing 9,9′-bianthracene-based dyes as a co-sensitizer

In this paper, we report two interesting metal-free organic co-sensitizers, which use fluorene or carbazole as the donor scaffold and are linked to cyanoacrylic acid via a 9,9'-bianthrylene pi-spacer. These organic dyes have a particular twisted structure, and their absorption spectra are complementary to the leading dye MK-3. We investigated the photophysical, electrochemical, and photovoltaic properties of these two co-sensitizers in detail. Interestingly, when the same concentration of MK-3 dye was co-sensitized with different concentrations of LD2, the performance of the devices did not show a linear change, and the best photovoltaic performance was obtained with sensitized device made with 0.2 mM MK-3 and 0.04 mM LD2. It displayed the power conversion efficiency (PCE) of 6.47 % with short-circuit current density (J(SC)) of 14.54 mA cm(-2), open-circuit voltage (V-OC) of 0.653 V and fill factor (FF) of 0.681. These results provide a reference for the optimization of the device by the method of co-sensitization; that is, selecting a suitable co-sensitizer at a suitable concentration may be one of the crucial factors.