Many salient Raman peaks selleck compound can be observed from the Rhodamine 6G (R6G) probe [27]. In comparison, different molar concentrations of R6G adsorbed on nanogold films shows a collection of spectra illustrating the efficiency of the SERS. As the molar concentration of R6G decreases, the intensity of the Raman spectra decreases. The junctions between the aggregated nanoparticles or nanoislands are believed to be SERS ‘hot spots’ where large field enhancements down to a single molecule are observed [28, 29]. This is the result of localized surface plasmon resonance coupled between the nanoparticles and enhanced electromagnetic

field intensity localized at the nanoparticle junctions [30]. Figure 4 SERS spectra of R6G adsorbed on the surface of the Au nanofilm/glass. Discussion To compare the impact of continuous ultrathin gold nanofilms on the absorption of visible light, plasmonic enhancement of the P3HT:PCBM bulk heterojunction system is demonstrated in a spin-cast device with EPZ015938 purchase an incorporated continuous ultrathin gold nanofilm thicknesses of 2 nm

or so which are chosen to be sufficiently thin to limit the amount of light absorbed before reaching the active layer. The nanofilm incorporated with gold in the active P3HT:PCBM layer is shown to have significantly greater absorbance enhancement than the nanofilm without gold in the entire excitation spectral range in Figure 3. As shown in Figure 2, the optical absorption spectrum of the continuous ultrathin gold nanofilm has high light transmittance and broad surface plasmon resonance band in the wavelength range of 300 to 1,000

nm. Therefore, the results Selleck ZD1839 demonstrate that the enhancement of absorption in the wavelength range of 350 to 1,000 nm is due to the surface plasmon resonance absorption. The much higher plasma frequency of Au ensures a better overlap between plasmon resonance and absorption band of organic semiconductors. The light energy is trapped mainly in the P3HT:PCBM layer, leading to enhanced absorption in the active layer. For the ITO/Au film/PEDOT:PSS/Au film/P3HT:PCBM and ITO/PEDOT:PSS/Au film/PEDOT:PSS/Au film/P3HT:PCBM structures, the plasmon resonance is located at a wavelength range of 350 to 1,000 nm. The plasmonic peak better overlaps the P3HT:PCBM absorption band. These enhancements concerning light absorption in the visible region can be explained by the surface plasmon polariton resonance of metallic nanoparticles in the gold nanofilm. When metallic nanoparticles are in close proximity, their plasmon resonances couple with each other and generate a light-scattering spectrum that depends strongly on the interparticle distance. The two-dimensional distinctive ultrathin continuous gold nanofilms can be used as subwavelength antennas in which the plasmonic near-field is coupled to the organic semiconductor, Apoptosis inhibitor increasing its effective absorption cross section.