Plasmon Enhanced Spectroscopy of N,N′-Dialkylquinacridones Used as Codopants in OLEDs

• Published in: Journal of physical chemistry. C Vol. 115; no. 34; pp. 16838 - 16843
• Main Authors: del Puerto, Elena, Domingo, Concepción, Sanchez-Cortes, Santiago, García-Ramos, Jose V, Aroca, Ricardo F
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.09.2011
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp204366g

Plasmon-enhanced Raman scattering and plasmon-enhanced fluorescence of the two molecules N,N′-dimethylquinacridone (DMQA) and N,N′-diisoamylquinacridone (DIQA) used as codopants in OLEDs (with improved stability) are reported. The work includes a complete vibrational characterization using Raman and infrared spectra supported by DFT calculations. Plasmon enhancement is achieved using silver and mixed Ag/Au nanostructures: colloids and metal island films, supporting localized surface plasmon resonances (LSPR). However, fine-tuning of the experimental conditions is necessary to attain surface-enhanced (resonance) Raman scattering (SERS/SERRS) of the two molecules with similar structures. SERRS spectra of DMQA are obtained on silver colloids and from a Langmuir–Blodgett (LB) monolayer deposited onto silver island films (SIF). High quality SERRS spectra of DIQA were only obtained from LB layers on mixed Ag/Au island films. Using spacer LB layers of arachidic acid (AA) to separate the fluorophore from the metal nanostructure, surface-enhanced fluorescence (SEF) spectra for both quinacridones were obtained on silver island films. The spectral data provided information on the subject of the molecular aggregation in the LB layers.