Plasmonic Absorption Enhancement in Organic Photovoltaics

ABSTRACT Organic solar cells have a strong potential for the near future, because their material and fabrication costs can be much smaller than for traditional technologies. However, in order to become commercially viable their efficiency needs to increase. One of the novel, interesting techniques to increase the light absorption is by including plasmonic enhancements DESCRIPTION Subwavelength-scale metallic structures exhibit intricate enhancement and scattering effects. We rigorously model these effects in thin-film cells using the frequency domain finite element software COMSOL. For nanoscale metallic particles incorporated inside the active layer the main physical enhancement effect is due to a local increase of the fields Figure 1: (a) Schematic of the electrode system. (b) Example of an absorption spectrum for the planar and patterned device (period=400nm, fill factor=0.5, triangle height=120nm). (c) Plot of the norm of the magnetic field profile for TM polarization at 640nm wavelength (peak indicated by A in (b)). CONCLUSION Plasmonic elements can increase the absorption efficiency of thin-film organic structures. Both metallic nanoparticles and patterned electrodes are studied with rigorous numerical methods. With silver nanoparticles (24 nm diameter) we observe an enhancement with a factor of around 1.56 in a 33 nm thick active layer, bringing the structure to the absorption level of much thicker active layers without nanoparticles ACKNOWLEDGEMENTS We acknowledge the Fund for scientific research -Flanders (FWO Vlaanderen), IWT-SBO No.060843 "Polyspec", grant No. IAP P6-10 "photonics@be" and COST Action MP0702. REFERENCES [1]