Optical confinement can induce enhancement of the resonance energy transfer between fluorescent molecules by influencing the interaction between the different available energy levels. We study the energy transfer between a pair of molecules, tris(2-phenylpyridine) iridium and bis(2-methyl-8-quinolinato)-4-phenylphenolate aluminum, which are extensively used in organic light-emitting diode technologies. These molecules have previously shown Förster energy transfer. We present the result of the dipolar coupling of these two molecules embedded in a poly(N-vinylcarbazole) film and inserted in a colloidal photonic crystal. Due to the presence of the photonic band gap, the efficiency of the energy transfer has been improved. A thermal study of the emission under the effect of the photonic band gap has been performed.
Building photonic crystals by combination of colloidal ordering and metal sputtering we were able to construct a
system sensitive to an electrical field. In corresponding crystals we embedded the Dexter pair (Ir(ppy3) and BAlq) and
investigated the influence of the band gap on the resonant energy transfer when the system is excited by light and by
an electric field respectively. Our investigations extend applications of photonic crystals into the field of
electroluminescence and LED technologies.
Faraday rotation for magnetic field sensing can find applications in satellite altitude monitoring. Enhancing and tuning
Faraday rotation is demonstrated in hybrid magnetic photonic crystals, based on an independent nanoscale engineering of
two different materials (silica and iron oxide) at different length scales (< 20 and > 200 nm). An engineering approach
towards combined photonic band gap properties and magnetic functionalities, based on independent nanoscale
engineering of two different materials at different length scales, is conceptually presented, backed by simulations, and
experimentally confirmed. Large (> 200 nm) monodisperse nanospheres of transparent silica self-assemble into a
photonic crystal with a visible band gap, which is retained upon infiltration of small (< 20 nm) nanoparticles of magnetic
iron oxide. Enhancing and tuning Faraday rotation in photonic crystals is demonstrated.
Photonic crystals have become an extremely active area of research, holding much potential for improvement and
miniaturization of optical technology, just like semiconductors caused a revolution in electronics. A very popular sample
to study in the visible region has been the synthetic opal, made by self-assembly processes from monodisperse dielectric
spheres. Its high degree of symmetry and the nature of the dielectric materials usually employed do, however, limit its
effectiveness in some ways. Here, we present an experimental investigation of modifications to these materials, adding
enhanced magnetic interactions with the electromagnetic field and different shapes to the photonic crystal toolbox, as
well as a combination of both.
The fluorescence of chromophores embedded in a photonic crystal is inhibited by the presence of a photonic pseudo-gap. We present the influence of such an incomplete bandgap on the emission and energy transfer by studying the steady-state and time-resolved emission properties of both a donor and an acceptor fluorophore in a self-assembled photonic crystal. Our results clearly show an inhibition of the donor emission and a concomitant enhancement of the acceptor emission, indicating improved energy transfer from donor to acceptor. This is explained by the decreased number of available
photonic modes for radiative decay for the donor in a suitable engineered photonic crystal with respect to in the effective
The fluorescence of emitters embedded in a photonic crystal is known to be inhibited by the presence of a photonic
pseudo-gap acting in their emission range. Here we present a comparative study of the influence of the pseudo-gap on
the fluorescence emission of either organic dyes or nanocrystals embedded within a photonic crystal. Our results clearly
show that the optical properties of the emitters are primarily controlled by the presence of a pseudo-gap which causes
inhibition of the emission in both cases, regardless of the differences in chemical composition. These findings are mainly
attributed to a decrease of the number of available photonic modes for radiative decay of the emitter in a photonic crystal
compared to the effective homogeneous medium. Furthermore, we show that a photonic crystal can be used to control
the fluorescence energy transfer (FRET) between donor-acceptor (D-A) pairs of dyes. Finally, we show that the
application of an external magnetic field can finely tune the emission characteristics of emitters with a permanent