Polymer blends in organic LEDs offer the advantage of processibility coupled with flexibility with respect to the chromophores which can be incorporated into their structures. The polymer matrix is also though to have a positive effect on the quantum efficiency and other LED performance indicators. Two‐layer devices have also been shown recently to yield improved performances. Here, a two‐layer device based on polymer blends is reported.

%'e show that low-temperature fluorescence spectra of large high-quality Ctl single crystals are mainly composed of several, independent pairs of T&~false origins. In analogy to the case of anthracene single crystals the series of emission bands can be interpreted in terms of exciton (Frenkel) emission from so-called E traps. Temperature dependent luminescence experiments support this interpretation.

No abstract

No abstract

We report on the design and the optical properties of a spin-coated multilayer organic microcavity. Tri(stilbene)amine blended with polysulfone as the first layer and an oxadiazole derivative (BPBD) blended with polystyrene as the second layer are sandwiched between two planar mirrors. Enhancement of the luminescence and spectrally narrow emission are observed. By means of time resolved luminescence spectroscopy we show that the spontaneous emission rate is increased in the cavity.

PACS. 78.47 -Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter.

No abstract

We present the first experimental observation that dipole-dipole interaction can be strongly enhanced by placing the system in a microcavity. We have studied the excitation energy transfer in poly(phenyl-p-phenylene vinylene) (PPPV) doped with DCM molecules, placed within a Fabry-Perot resonator. As the spectral position of the cavity resonant mode in tuned across the DCM absorption profile, the transfer efficiency from PPPV to DCM changes dramatically as revealed by photoluminescence (PL) spectra. This behavior is clear evidence for the increase of the dipole-dipole interaction strength at the cavity resonances mediated by propagating modes emitted from the excited dipoles.