The effect of [email protected] nanostructure of [email protected]₂ on the spectral-luminescence properties of polymethine dye (PD) functionalized with sulfonate group and its photovoltaic properties in the PD dye-sensitized solar cell were investigated. Quenching in the fluorescence intensity of PDs molecule by almost 3 times was observed for the dye-absorbed titanium dioxide porous film. Furthermore, the decreasing effect in fluorescence lifetime was found to be significant for the PD molecules modified with functional groups. In the presence of [email protected]₂ nanoparticles (NPs), an increase in the luminescence intensity of PD by 60 – 90 % was observed. A mechanism of plasmon nanoparticles’ effect on the decay of the excited states of dye molecules was proposed. The efficiency of PD-sensitized solar cells was increased by 1.2 times for PD 1 and 2.0 times for PD 2. The enhancement in the efficiency is result from the growth in the spectral sensitivity of solar cell in the region of 400 – 450 and 600 – 700 nm and a change in the charge-transport parameters of TiO₂ films. This increase was supported by a decrease in the resistance at the semiconductor–dye interface by 8.2 times for PD 1 and 22.4 times for PD 2 that leads to the growth in the part of photoelectrons reaching the counter electrode in solar cell with plasmon NPs.