Charge Transfer on the Surface-Enhanced Raman Scattering of Ag/4-MBA/PEDOT:PSS System: Intermolecular Hydrogen Bonding

A sandwich-structured noble metal-probe molecule-organic semiconductor consisting of Ag nanoparticles (NPs), 4-mercaptobenzoic acid (4-MBA) and different concentrations poly(styrenesulfonate:poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) was prepared by layer-by-layer assembly. Intermolecular hydrogen bonding observed to have a significant effect on the surface-enhanced Raman scattering (SERS) Ag/4-MBA/PEDOT:PSS. Upon increasing PEDOT:PSS concentration, characteristic band intensity 4-MBA enhanced. In addition, selected b2 vibration mode significantly enhanced due influence charge transfer (CT) mechanism. The CT degree (?CT) composite system calculated before after doping with PEDOT:PSS; when concentration 0.8%, SERS tended be stable, ?CT reached maximum. Compared that undoped system, doping, which can explained induced bonds. These results indicate transfers from Fermi energy level lowest unoccupied molecular orbital (LUMO) 4-MBA, resulting potential difference, will continue LUMO PEDOT:PSS. Therefore, introduction organic semiconductors into field not only expands substrate scope, but also provides new idea for exploring bonds has become an important guide study structure systems.