| Energy Transfer in Organic and Hybrid Blends |
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Page 2 of 2 Recently, we also focussed on hybrid organic/inorganic materials, which are a fast growing research area, since a lot of basic and practical interest has been raised by their optical and mechanical properties.
These hybrid materials can benefit from the unique properties of both the organic and the inorganic components. Generally, light-emitting conjugated polymers constitute the organic component of optically active hybrid materials, because of their ease of processing and good opto-electronic characteristics. For the inorganic component, semiconductor and oxide micro- and nanocrystals are the most exploited materials, since they can provide a homogeneous dispersion inside the organic component and a more effective charge transfer in the composite. The interactions between the inorganic and the organic component inside a hybrid material can be mediated by radiative or nonradiative energy transfer. We carried out an extensive study of the energy transfer in hybrid inorganic-organic composite system, composed by an inorganic oxide micro-crystal as donor (ZnO) and an organic conjugated polymer as acceptor (MEH-PPV) (Fig. 2). To investigate the dependence of the energy transfer rate on temperature, we studied the temperature behaviour of the relative PL intensity (φ) from the acceptor molecules for composites with different A:D relative concentrations (Fig. 3). Upon decreasing temperature, the relative PL intensity (φ) decreases, the specific decrement depending on the donor/acceptor relative concentration. The T-dependence of the energy transfer has to be mainly related to changes in the donor and acceptor quantum efficiency and decay channels. The quantitative understanding of non-radiative processes in hybrid inorganic-organic materials is fundamental for the development of optimized hybrid organic/inorganic light-emitting devices and lasers whose spectral emission rely on energy transfer in active nanocomposite media.
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