Abstract
Environmentally friendly purely organic dye-sensitizedbased solar cells and photoelectrochemical cells have emerged as primary photovoltaic technologies due to their stabilities, cost effectivenesses, and equally high efficiencies compared to conventional ruthenium-based dyes. Nevertheless, back electron hole recombination, fast electron injection, wide band light harvesting, and environmental hazards are crucial aspects that govern advancement in photovoltaic technology. Organic photosensitizers having a delocalized p system of electrons end capped with electron acceptors (A) and donors (D) have easy synthesis methods, excellent abilities to confine solar energy, and exceptional tunable absorbances and have the potential to overcome the above-mentioned crucial aspects in combination with semiconductor-metal (plasmonic) nanohybrids. Here, we have reported enhanced photovoltaic activity of organic D-p-A type photosensitizer (RK1)-based plasmonic Au nanoparticle-decorated hybrid mesoporous TiO2 photoanodes in dye-sensitized solar cells (DSSCs) and in dye-sensitized photoelectrochemical water splitting (DSPEC). The presence of plasmonic material not only reduces the back electron hole recombination but also the spectral overlap of its localized surface plasmon resonance (LSPR) band with that of organic sensitizer RK1 in close proximity to the TiO2 surface, leading to the possibility of Fo<spacing diaeresis>rster resonance energy transfer (FRET) which further enhances the device performance. Further, an ultrafast spectroscopic study has been performed to study the excited-state charge and energy transfer dynamics of the interfaces of the nanohybrids. Our analysis demonstrates the identification of a specific unique combination of the nanohybrid which is useful to design a new generation of solar light-harvesting materials, especially in the case of DSPECs.