Electrically responsive photonic crystals: A review

Tunable photonic crystals (TPCs) represent an important class of intelligent materials, which can be used as optically active components and as functional technology to change an object's colour. Among these smart structures, electrically responsive photonic crystals are the most promising for real technological applications. Up to now, to transform the electrical stimulus into an optical response several strategies have been adopted that can be classified into (1) electrochemical processes, (2) reorientation of liquid crystal molecules, (3) electrophoretic organization of colloidal suspension and (4) indirect electrically induced modification of the photonic structures. In this review article, these approaches are systematically summarized and analysed with a particular emphasis on the chemistry of materials