Fast electrically driven photonic crystal based on charged block copolymer

We have developed electrically driven photonic crystals (PCs) from a quaternized polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) block copolymer which can form a one dimensional periodic lamellar structure. The variation of applied voltage from -4.50 to +2.36 V on the PCs can lead to color display over the entire visible region with a sub-second fast response, where the periodic structure swells from 4.3 to 7 times that at dry state. The fast response is attributed to the charging of the P2VP block. Besides, the photonic crystal exhibits a reverse volatility behavior, that is, as the applied voltage increases, the reflective peak wavelength decreases. Such fast switching PCs are facilely prepared with low driving voltage and good durability. The PCs are expected to find applications in information technologies.