Molecular packing effects on the optical spectra and triplet dynamics in oligofluorene films.
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-Tn 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 (beta) of 3.4 x 10 (-14) and 1.1 x 10 (-15) cm3 s (-1) for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films.
Cabanillas-Gonzalez
Juan
J
IFN-CNR, Dipartimento di Fisica, ULTRAS-INFM, Politecnico di Milano, Milano 20133, Italy. juan.cabanillas@polimi.it
Sciascia
Calogero
C
Lanzani
Guglielmo
G
Toffanin
Stefano
S
Capelli
Raffaella
R
Ramon
Miguel C
MC
Muccini
Michele
M
Gierschner
Johannes
J
Hwu
Tsyr-Yuan
TY
Wong
Ken-Tsung
KT