3,4-Ethylenedioxythiophene as an electron donor to construct arylamine sensitizers for highly efficient iodine-free dye-sensitized solar cells

Abstract

The development of arylamine photosensitizers with high extinction coefficients, and suitable electronic structures and steric properties is necessary for improving the efficiency of dye-sensitized solar cells (DSCs) employing iodine-free redox shuttles. A new truxene-based organic sensitizer, M20, incorporating a 3,4-ethylenedioxythiophene (EDOT) moiety as an electron donor was synthesized and compared to its reference sensitizer, M4. M20 sensitized DSCs employing the Co(II/III) tris(1,10-phenanthroline)-based redox electrolyte exhibit a short circuit photocurrent of 11.8 mA cm⁻², an open circuit voltage of 903 mV, and a fill factor of 0.69, corresponding to an overall conversion efficiency of 7.35% under standard AM 1.5 sunlight, which is higher than that of 6.86% for equivalent M4 sensitized DSCs. The effects of 4-tert-butylpyridine (TBP) as an additive on the photovoltaic performance of truxene-dye-sensitized nanocrystallineTiO₂ solar cells were also investigated.