New dimensions in light energy conversion

Flexible in shape, color and application

Optical Additives GmbH's product ZeoFRET® is a brand new, revolutionary additive for transparent polymers. This technology transforms polymers so that they can serve as a light harvester. The harvested light is transferred to a solar cell in order to produce electricity. This concept is called "luminescence concentrator".

You may use this material to cast or to coat the body of any device which then as a whole feeds small embedded solar cells with concentrated light. The device bodies can be any shape and color.

Examples of how to coat ZeoFRET® on a substrate:

Advantages compared to classical silicon cells used in mobile devices:

  • Different colors can be provided with no change to the solar-energy conversion functionality (you don't realize that you hold solar cells in your hands)
  • Diffuse light, artificial light, sun-light: all sources of light work
  • Partial shadowing of the device body is not an issue
  • The whole body of a device can be used as light trap (increasing efficiency)
  • The device body can be any shape
  • The material can be mixed into polymers or coated on all sorts of mineral glass and polymers (simple and low cost production)
  • Significantly fewer solar cells are needed for the same amount of power generation (increasing efficiency and cost savings)

The concept of luminescence concentrators has been studied for over 30 years. Optical Additives GmbH re-invented it and eliminated historical drawbacks of this concept. The key ZeoFRET® innovation solved the problem of re-absorption of light traveling through the wave guide by driving down to a minimum the overlap between absorption and emission of the luminescence centers.

ZeoFRET® is a multi-dye material using Förster Resonance Energy Transfer (FRET) for wavelength conversion. The principle is shown in the following picture. Each colored rectangle (blue, yellow and red) symbolizes a dye molecule with different absorption spectrum.

Light is absorbed by any of the dyes. The energy is then transferred to the dye with the lowest energy level (red colored dye in the picture). From there, the energy can be emitted (luminescence) or used to sensitize a nearby semiconductor.

This technology reduces re-absorption of the emitted light to a minimum.

Example of Absorption and Emission spectra of coated plate with orange ZeoFRET® (right picture)

Depending on the requirements of an application, the types and numbers of absorber and emitter dyes can be selected (see color samples shown below).

Examples of different colors of ZeoFRET® material:


  • EU Patents: 1873202; 2291484
  • US Patents: 7,655,300 B2; 8,917,969
  • China Patents: 7CN101100535B; ZL 2009 8 0125078.3
  • Japan Patent: 4984238
  • Korea Patent: 10-1361434
  • Further patents pending
  • ChemEurJ (Chemistry a European Journal) (2016): Supramolecular Organization of Dye Molecules in Zeolite L Channels: Synthesis, Properties and Composite Materials (Dr. Pengpeng Cao, Dr. Oleg Khorev, Dr. André Devaux, Lucie Sägesser, Dr. Andreas Kunzmann, Prof. Achim Ecker, Prof. Robert Häner, PD Dr. Dominik Brühwiler, Prof. Gion Calzaferri, Prof. Peter Paul Belser)
  • Chemistry of Materials (2014), 26, 6878−6885: Efficient and Robust Host−Guest Antenna Composite for Light Harvesting (André Devaux, Gion Calzaferri, Peter Belser, Pengpeng Cao, Dominik Brühwiler and Andreas Kunzmann)
  • Advanced Functional Materials (2007), 17, 2298-2309 and Cover page: Transparent Zeolite-Polymer Hybrid Materials with Tuneable Properties (Stéphane Suárez, André Devaux, Jorge Bañuelos, Olivia Bossart, Andreas Kunzmann, Gion Calzaferri)
  • Solar Energy Materials & Solar Cells 91 (2007) 986–995: Advanced photon-harvesting concepts for low-energy gap organic solar cells
  • (R. Koeppe, O. Bossart, G. Calzaferri, N.S. Sariciftci)
  • SPIE 2008, 10.1117/2.1200805.1162, Dye in nanochannels boosts performance of artificial photonic antenna systems (Gion Calzaferri)
  • Journal of Materials Chemistry 19 (2009) 8040–8067: Nanochannels for supramolecular organization of luminescent guests
  • (D. Brühwiler, G. Calzaferri, T. Torres, et al.)