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In this letter, employing the spectroscopic ellipsometry, we study the phenomena of molecular reorientation in amorphous thin films of a ter(9,9-diarylfluorene) compound T3 upon annealing around or above its glass transition temperature. Molecular reorientation results in changes in the in-plane optical constants, which in turn could alter the waveguiding characteristics of a thin-film slab waveguide. Employing such properties, we demonstrate continuous tuning of the wavelength of amplified spontaneous emission of a T3 slab waveguide within one sample. Such an approach has the particular advantage of permitting facile tuning of stimulated emission after device fabrication. [ABSTRACT FROM AUTHOR]

We report charge-transport and related physical properties of terfluorenes with various C9 substitutions. Results show that by introducing slight spiroconjugation between a core chromophore and conjugated substitutions through spiro-linking, the bulky substitution not only serves as a spatial hindrance to enhance morphological stability and emission efficiency in thin films, but also bridges and enhances intermolecular charge transport under certain situations. Interestingly, such characteristics are acquired without altering major electronic properties of core chromophores, rendering it a flexible molecular scheme for tuning characteristics of functional molecules to meet various demands of different applications. [ABSTRACT FROM AUTHOR]

Optical characteristics of microcavity organic light-emitting devices (OLEDs) having two metal mirrors are examined. Analyses show that a high-reflection back mirror and a low-loss high-reflection exit mirror are essential for such microcavity devices to obtain luminance enhancement relative to conventional noncavity devices. An enhancement of 2 in cd/A efficiencies has been experimentally achieved for microcavity top-emitting OLEDs using an exit mirror composing thin metal and dielectric capping. The capping layer in the composite mirror plays the role of enhancing reflection and reducing absorption loss, rather than enhancing transmission. [ABSTRACT FROM AUTHOR]