In:
Journal of Applied Physics, AIP Publishing, Vol. 95, No. 3 ( 2004-02-01), p. 881-886
Abstract:
This article reports on the investigation of anisotropic optical properties of vacuum-deposited thin films of high-efficiency blue-emitting ter(9,9-diarylfluorene)s using variable-angle spectroscopic ellipsometry. Under deposition conditions typical for thin-film organic devices, both real and imaginary parts of refractive indices of vacuum-deposited ter(9,9-diarylfluorene) films exhibit rather significant uniaxial anisotropy with the optical axis along the surface normal. In particular, for the absorption associated with the π–π* transition of the terfluorene backbone, they show substantially larger in-plane extinction coefficients than the out-of-plane extinction coefficients. It is thus inferred that the vacuum-deposited ter(9,9-diarylfluorene) molecules tend to align their molecular axes and π–π* transition dipole moments along the substrate surface as observed previously in spin-coated films of alkyl-substituted polyfluorenes or oligofluorenes, even though the present ter(9,9-diarylfluorene)s have rigid and bulky aryl substituents on C9, relatively shorter oligomer chains, and very different deposition conditions.
Type of Medium:
Online Resource
ISSN:
0021-8979
,
1089-7550
Language:
English
Publisher:
AIP Publishing
Publication Date:
2004
detail.hit.zdb_id:
220641-9
detail.hit.zdb_id:
3112-4
detail.hit.zdb_id:
1476463-5
Permalink