Light-propagation patterns in freestanding two-dimensional colloidal crystals

This paper reports the preparation of freestanding two-dimensional (2D) particle arrays, which fine particles are packed in highly dense and oriented manner. To fabricate freestanding 2D arrays, sintering process of the polymer particles (3.06, 1.034, and 0.491 μm diameter) was examined. The sintered 2D particle arrays on glass substrates were easily peeled off as a freestanding film by soaking into water. The freestanding 2D particle arrays were stable enough in room temperature. They show the iridescent colors due to their optical periodicity. To convince the layer number of those freestanding 2D particle arrays, fluorescent polystyrene particles were added in the arrays. Fluorescent light propagation patterns in the arrays suggest that the freestanding films were monolayers. The transmission spectra of the freestanding film were also examined.