Abstract:
This work reports the multifunctionality of a novel Ru based dye (RuC) in enhancing the
performance of nanocrystalline Titanium dioxide (TiO2) / Poly (3-hexylthiophene) (P3HT) hybrid solar cells.
TiO2 / P3HT nanocomposite films were fabricated with and without the RuC dye as the interface modifier
and their optical properties were tested using UV-Vis and photoluminescence (PL) spectroscopies. UV-Vis
spectra of TiO2 / RuC and TiO2/RuC/P3HT films ensure that the absorption spectra is broadened in the UV
region due to the addition of the RuC dye. The PL measurements were carried out by pumping with laser
at wavelength corresponds to maximum absorption of P3HT. The PL of TiO2 / P3HT nanocomposite films
were significantly quenched when the RuC dye was introduced at the TiO2 / RuC interface. The PL quenching
ensure the efficient exciton dissociation in P3HT when RuC is introduced. The corresponding solar cells
were then fabricated using successive evaporation of MoO3 and silver on top of the films and characterised
under monochromatic and under Air Mass (AM) 1.5 conditions (100 mW cm−2, 1 sun). The insertion of the
RuC dye suppresses the dark current while extends external quantum efficiency spectra. As such, device
with dye shows improved open circuit voltage and more than a factor of two times higher short circuit
current density in comparison with the corresponding control. Hence, RuC dye improves the power
conversion efficiency by a factor of two. This study concludes that, RuC dye has dual role; extending the
spectral response and suppressing the dark current.
