“Nonresonance” Enhancement of Optical Absorption in Organic Films with Plasmonic Particles

Visible light absorption by organic chromophores enhanced due to their interaction with metal nanoparticles is of great interest as an approach to increasing the efficiency of photovoltaic cells and photocatalysts. Since chromophores capable of aromatic stacking interactions are often used as organic components, investigation of the conditions for the enhancement of optical absorption in systems based thereon is of fundamental importance. Ultrathin layered systems based on perylene-3,4,9,10-tetracarboxylic acid isopentyldiimide and diverse two-dimensional plasmonic assemblies of gold nanoparticles are studied in this work. An additive spectral behavior is observed for a system containing individual (nonaggregated) nanoparticles in spite of the coinciding absorption spectra of the components. At the same time, enhancement of optical absorption by 35% is realized in a system based on assemblies of nanoparticle aggregates in the absence of the coincidence between the spectral characteristics of the plasmonic and organic components. These results provide new opportunities to control the interaction of light with ultrathin films of chromophoric dyes used to create organic optical and optoelectronic devices.