Optical physics

We focus on studies of light interacting with nanostructured materials, in both experiment and theory. Our motivation for this is to improve e. g. the in- and out-coupling of light into nanostructures which is of importance for electro-optical devices.

Project areas:

Modelled electrical field intensities for different nanowire arrays at peak absorptance of light. Graphics: Yang Chen. Further reading: Appl. Phys. Lett. 110, 081104 (2017); https://doi.org/10.1063/1.4977032

Designed strong incoupling of light into nanostructures

It is not easy to couple light into nanowires if the nanowires are smaller than the wavelength of light. We thus study this incoupling theoretically as well as experimentally and the longterm aim is to maximise the incoupling. This has in particular been done for arrays of nanowires where the array itself is larger than the wavelength of light, but the individual nanowires are smaller than the wavelength of light. The incoupling is dependent on the dielectric function of the material

Optimisation of solar cells

As an important application of Optical Physics we study the efficiency of nanowire solar cells as a function of the geometry of the solar cells. This involves a detailed knowledge of the light intensity inside the nanowires as well as a good model for the carrier generation and subsequent generation of current. It is now possible to realistically model a nanowire solar cell including contacts and possible polymer filling between the nanowires

Key publications

InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit. J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, M. T. Borgström. Science 339, no. 6123 (2013): 1057-1060. DOI: 10.1126/science.1230969.
See article InP nanowire array solar cells at publisher's site

Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling. Y. Chen, P. Kivisaari, M.-E. Pistol, and N. Anttu. Nanotechnology 27, no. 43 (2016): 43540
See article optimization of the short-circuit current at publisher's site

Geometrical optics, electrostatics, and nanophotonic resonances in absorbing nanowire arrays. Anttu, Nicklas. Optics letters 38, no. 5 (2013): 730-732. https://doi.org/10.1364/OL.38.000730
See article geometrical optics at publisher's site