Dr. Gion Calzaferri Profile

Dr. Gion Calzaferri

at Univ Bern

SPIE Involvement:

Author

Proceedings Article | 23 April 2008 Paper

Mimicking the antenna system of green plants

Gion Calzaferri, Huanrong Li

Proceedings Volume 7002, 700202 (2008) https://doi.org/10.1117/12.787026

KEYWORDS: Molecules, Zeolites, Crystals, Antennas, Fluorescence resonance energy transfer, Energy transfer, Semiconductors, Luminescence, Solar energy, Solar cells

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Artificial photonic antenna systems have been realised by incorporating organic dyes in a nanoporous material. We have been using zeolite L in most of our experiments as it has proven to be a very versatile host. Its crystals are cylindrically shaped porous aluminosilicates featuring hexagonal symmetry. The size and aspect ratio of the crystallites can be tuned over a wide range. A nanometre sized crystal consists of many thousand one-dimensional channels oriented parallel to the cylinder axis. These can be filled with suitable organic guests. Geometrical constrains of the host structure lead to supramolecular organisation of the guests in the channels. Thus very high concentrations of non- or only very weakly interacting dye molecules can be realised. A special twist is added to these systems by plugging the channel openings with a second type of fluorescent dye, which we call stopcock molecule. The two types of molecules are precisely tuned to each other; the stopcocks are able to accept excitation energy from the dyes inside the channel, but cannot pass it back. The supramolecular organisation of dyes inside the zeolite channels is what we call the first stage of organization. It allows light harvesting within the volume of a dye-loaded zeolite L crystal and also radiationless energy transport to either the cylinder ends or centre. The second stage of organisation represents the coupling to an external acceptor or donor stopcock fluorophore at the ends of the zeolite L channels, which can then trap or inject electronic excitation energy. The third stage of organization is realised by interfacing the material to an external device via a stopcock intermediate. We observed that electronic excitation energy transfer in dye-zeolite L materials occurs mainly along the channel axis. This important finding means that macroscopically organised uni-directional materials can be prepared. In order to achieve this, we prepared oriented zeolite L monolayers, filled them with luminescent dyes, and finally added a stopcock. The new materials offer unique possibilities as building blocks for optical, electro-optical and sensing devices.

Proceedings Article | 12 May 2006 Paper

Luminescence quenching measurements on zeolite L monolayers

Rodrigo Albuquerque, Arantzazu Zabala Ruiz, Huanrong Li, Luisa De Cola, Gion Calzaferri

Proceedings Volume 6197, 61970B (2006) https://doi.org/10.1117/12.661488

KEYWORDS: Zeolites, Luminescence, Crystals, Oxygen, Photonic crystals, Ruthenium, Supramolecular assemblies, Diffusion, Glasses, Antennas

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Proceedings Article | 12 May 2006 Paper

Light-harvesting host-guest antenna materials for solar energy conversion devices

Stefan Huber, Gion Calzaferri

Proceedings Volume 6197, 619708 (2006) https://doi.org/10.1117/12.661153

KEYWORDS: Molecules, Zeolites, Crystals, Antennas, Energy transfer, Luminescence, Solar energy, Photonic crystals, Semiconductors, Molecular photonics

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In natural photosynthesis, light is absorbed by photonic antenna systems consisting of a few hundred chlorophyll molecules. These devices allow fast energy transfer from an electronically excited molecule to an unexcited neighbour molecule in such a way that the excitation energy reaches the reaction centre with high probability. Trapping occurs there. The anisotropic arrangement of the chlorophyll molecules is important for efficient energy migration. In natural antennae the formation of aggregates is prevented by fencing the chlorophyll molecules in polypeptide cages. A similar approach is possible by enclosing dyes inside a microporous material and by choosing conditions such that the cavities are able to uptake only monomers but not aggregates. In most of our experiments we have been using zeolite L as a host because it was found to be very versatile. Its crystals are of cylindrical shape and consist of an extended one-dimensional tube system. They can be prepared in wide size range. We have filled the individual tubes with successive chains of different dye molecules and we have shown that photonic antenna materials can be prepared. Moreover, fluorescent dye molecules can be bound covalently to the channel entrances. Dependent on the spectral properties of these stopcock molecules, the electronic excitation energy is transported radiationless to the stopcock fixed at the ends of the nanochannels or injected from the stopcock to the dyes inside the zeolite. The radiationless energy migration is in competition with spontaneous emission, thermal deactivation, quenching, and photochemically induced degradation. Fast energy migration is therefore crucial for an efficient antenna material. - The supramolecular organization of the dyes inside the channels is a first stage of organization. It allows light harvesting within the volume of a dye-loaded zeolite L crystal and radiationless transport to both ends of the cylinder or from the ends to the centre. The second stage of organization is the coupling to an external acceptor or donor stopcock fluorophore at the ends of the zeolite L channels, which can trap or inject electronic excitation energy. The third stage of organization is the coupling to an external device via a stopcock intermediate. The wide-ranging tunability of these highly organized materials offers fascinating new possibilities for exploring excitation energy transfer phenomena, and challenges for developing new photonic devices for solar energy conversion and storage.

Proceedings Article | 20 April 2006 Paper

Light-harvesting host-guest antenna materials for photonic devices

Gion Calzaferri, Stefan Huber, André Devaux, Arantzazu Zabala Ruiz, Huanrong Li, Olivia Bossart, Le-Quyenh Dieu

Proceedings Volume 6192, 619216 (2006) https://doi.org/10.1117/12.665510

KEYWORDS: Zeolites, Crystals, Molecules, Antennas, Absorption, Luminescence, Semiconductors, Silicon, Energy transfer, Solar cells

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Proceedings Article | 20 April 2006 Paper

Electronic excitation energy transfer from dye-loaded zeolite L monolayers to a semiconductor

Huanrong Li, André Devaux, Arantzazu Zabala Ruiz, Gion Calzaferri

Proceedings Volume 6195, 61951G (2006) https://doi.org/10.1117/12.661270

KEYWORDS: Zeolites, Molecules, Antennas, Silicon, Semiconductors, Crystals, Luminescence, Energy transfer, Absorption, Fluorescence resonance energy transfer

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Showing 5 of 6 publications

Conference Committee Involvement (5)