Synthesis and photovoltaic properties of organic sensitizers incorporating a thieno[3,4-c]pyrrole-4,6-dione moiety

Novel organic sensitizers containing a thieno[3,4-c] pyrrole-4,6-dione (TPD) moiety with triphenylamine or julolidine as the electron donor have been designed and synthesized for quasi-solid-state dye-sensitized solar cells (DSSCs). For comparison, two organic dyes based on a terthiophene spacer have also been synthesized. The absorption, electrochemical and photovoltaic properties of all sensitizers have been systematically investigated. We found that the incorporation of TPD is highly beneficial to broaden the absorption spectra of the organic sensitizers and prevent the intermolecular interaction. Therefore, the charge recombination possibility is reduced, which is revealed by the controlled intensity modulated photovoltage spectroscopy. A quasi-solidstate DSSC based on sensitizer FNE38 with TPD and triphenylamine moieties demonstrates a solar energy conversion efficiency of 4.71% under standard AM 1.5G sunlight without the use of coadsorbant agents.