Excited-State and Charge Carrier Dynamics in a High-Photovoltage and Thermostable Dye-Sensitized Solar Cell

Abstract

Apart from the harvesting of more infrared solar photons for a higher photocurrent, improving the photovoltage and thermal stability of a dye-sensitized solar cell are the other two key challenging issues for its performance enhancement. Herein we report a metal-free donor–acceptor dye (SC-4) characteristic of a triphenylamine-dihexylbithiophene electron donor and a benzothiadiazole-benzoic acid electron acceptor. This organic dye can be utilized for the fabrication of sensitized titania solar cells exhibiting excellent photovoltages of 1005 and 825 mV, respectively, when a volatile tris(1,10-phenanthroline)cobalt-based electrolyte and a nonvolatile iodine-based ionic liquid composite electrolyte are applied, respectively. With respect to the control dye C239 using the traditional electron acceptor cyanoacrylic acid, dye SC-4 displays not only an enhanced photovoltage owing to slower interfacial charge recombination but also an improved stability of photocurrent and efficiency even under a long-term therm...