Photonic crystals for light trapping within organic solar cells

We propose a methodology allowing the design of the active layer of organic solar cells in the shape of a photonic crystal. An optimised photonic crystal allows trapping the light in a layer at specific wavelengths thanks to a coupling of a low group velocity mode called slow Bloch mode. This method is used to design two structures which allow to improve absorption of light in organic solar cells for wavelengths close to the band gap of an active layer composed of poly-3-hexylthiophene (P3HT) and [6,6]-phenyl-C61-butiryc acid methyl ester (PCBM). Nevertheless, while the first structure does not allow an efficient charges harvesting by the electrodes, the second structure can be beneficial for both the optical and the electrical properties of the cell thanks to the structuring of the Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) layer.