ИСТИНА

Surface plasmon enhancement of the optical properties of materials at the interfaces is a rapidly developing strategy for improving the efficiency of photocatalysis, dye sensitized solar cells and polymer optical elements. Herein, we suggest a new strategy for plasmon-resonance enhancing electronic absorption (PREA) in ultrathin layers of dyes by using 2D nanoparticle sensitizers. To fabricate plasmonic antennas (PA) on the ultra-thin layers of organic chromophores, the 18-nm gold nanoparticles are stabilized in the optically transparent crystalline film of fatty surfactants through a colloid-induced condensation of fatty surfactants on a surface of gold hydrosol [1]. The phase segregation of solidified organics and nanoparticles proceeds through the formation of 2D network of AuNPs. Because the aggregation of AuNPs results in a plasmon coupling, spectroscopic monitoring the changing optical properties makes it possible to select the structure with desirable spectral position of the maximum absorbance with a precision of nanometers. The antennas with SP absorbencies at wavelengths over 600 nm remain structurally and spectrally stable after transferring from the liquid surface onto the solid supports. To stabilize the PAs with maximal absorbencies in the range 530- 600 nm, we apply a controlled self-assembly of AuNPs in the tightly packed films of CeO2 nanoparticles with high refractive index on the surface of binary colloidal solutions. By varying the ratio of AuNPs to CeO2 NPs in the subphase, one can tune the position of SP band in the spectrum of the resulting colloidal film. Our strategy makes it possible to match precisely the position of maximum absorbance of PA with that of the material of solid support, on which this PA is immobilized, to achieve a resonance effect. We coupled variously tailored PAs with monomolecular films of several organic dyes with different chemistries to initiate directly observable PREA effect at selected wavelengths. For the dye exhibiting a number of absorption bands, we showed that the PREA effect can be realized in a selective manner with respect to the position of each of these bands by tailoring the structure of HTPA sensitizer.