Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 4: Hybrid Systems and Devices

SYOH 4.3: Talk

Thursday, March 11, 2004, 17:15–17:30, H37

Cascade energy transfer in bandgap modulated multilayer structures of CdTe quantum dots — •Thomas Franzl, Stefan Schietinger, Thomas A. Klar, Andrey L. Rogach, and Jochen Feldmann — Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität München, Amalienstr. 54, D-80799 Munich, Germany

We report on very fast and directed energy transfer leading to strongly increased excitonic densities in cascaded energy transfer structures (CET) made of CdTe quantum dots capped by short chain thiols. A systematic bandgap variation in one spatial direction is realized by a layer-by-layer technique using CdTe nanocrystals of stepwise increasing sizes in subsequent layers. We observe an efficient energy transfer towards the layer of largest quantum dots. In this layer the excitonic density increases by an order of magnitude in comparison to a layered system containing only one size of CdTe nanocrystals. These high excitonic densities in CET structures are especially interesting for optoelectronic devices such as nanocrystal LEDs or lasers.