Molecular Packing Effects on the Optical Spectra and Triplet Dynamics in Oligofluorene Films

• Published in: The journal of physical chemistry. B Vol. 112; no. 37; pp. 11605 - 11609
• Main Authors: Cabanillas-Gonzalez, Juan, Sciascia, Calogero, Lanzani, Guglielmo, Toffanin, Stefano, Capelli, Raffaella, Ramon, Miguel C, Muccini, Michele, Gierschner, Johannes, Hwu, Tsyr-Yuan, Wong, Ken-Tsung
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 18-09-2008
• Subjects: B: Macromolecules, Soft Matter
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp8044143

We report on the triplet spectra and dynamics in two types of oligomeric films deposited by two different techniques: thermal evaporation and spin coating. The different molecular arrangement in both films is manifested in a red shift of the absorption, PL, and T1−T n absorption spectra of the sublimated film relative to the spin-coated one. Triplet recombination dynamics studied with steady-state photoinduced absorption (PA) spectroscopy follow a dispersive bimolecular recombination model away from the trap filling regime. We obtained values for the triplet bimolecular recombination ratio (β) of 3.4 × 10−14 and 1.1 × 10−15 cm3 s−1 for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films.