6 February 2013 Micro-optical design of photochemical upconverters for thin-film solar cells
Author Affiliations +
J. of Photonics for Energy, 3(1), 034598 (2013). doi:10.1117/1.JPE.3.034598
All presently available types of solar cells transmit light with energies below their band gaps, foregoing energy. An elegant way toward overcoming these subbandgap losses and using a larger fraction of the incident light is the re‐shaping of the solar spectrum by upconversion (UC) of photons. Recently, first results on solar cells augmented by either lanthanide-based UC or triplet-triplet-annihilation UC in organic chromophores were presented. Both of these UC strategies are characterized by a nonlinear response on the illumination density under conditions relevant to solar energy conversion, opening a route for increasing the UC yield by concentrating the light. While operation of the whole cell under concentrated sunlight is in most cases undesirable, application of micro-optical focusing of the transmitted light in the upconverting layer is a promising strategy. In the present work, a more than two-fold enhancement of the current gain by UC behind an amorphous silicon solar cell through optimization of the upconverter optical design is demonstrated, including employing a focusing microstructured back reflector. The experimental data is rationalized using a simple ray tracing modeling approach, highlighting a further enhancement potential of a microstructured UC unit.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Tim F. Schulze, Yuen Yap Cheng, Tony H. Khoury, Maxwell Crossley, Bernd Stannowski, Klaus Lips, Timothy W. Schmidt, "Micro-optical design of photochemical upconverters for thin-film solar cells," Journal of Photonics for Energy 3(1), 034598 (6 February 2013). http://dx.doi.org/10.1117/1.JPE.3.034598

Solar cells

External quantum efficiency





Solar energy


Detailed balance: lifetimes and efficiencies
Proceedings of SPIE (September 11 2007)
Excavation of methane hydrate using COIL
Proceedings of SPIE (February 23 2006)
Fourier transform spectrum of H2S in 2000 9000...
Proceedings of SPIE (January 26 1994)
Laser processing of plastics
Proceedings of SPIE (March 31 1995)

Back to Top