3D Colloidal photonic crystal fabrication improved by AC fields for frequency conversion enhancement in photovoltaics

We report on the fabrication of high-quality 3D colloidal photonic crystals, whose finality is to modify the emission properties of frequency converters for photovoltaic applications. The band structure of the photonic crystals can be used to enhance the emission of down- and up-converters materials embedded in the 3D structures. However, in order to achieve an efficient conversion the first step is to obtain highly ordered templates with appropriated dimensions. We analyze here the photonic crystals obtained by the dip-coating or vertical deposition method. Moreover, by using perpendicular AC fields during the assembly of the nanospheres, the quality of the packed structures has been improved. The optical transmittance of the synthesized crystals has been measured, which presents a band gap in agreement with the calculations, and a transmittance at the band gap as low as 0.5% for the thickest films.