Soft Material–Based Photonic Crystal

Taking inspiration from natural photonic crystals, the need for developing “soft materials” that can change color in response to external stimuli is increasing as photonic crystal technology progresses. These materials can be used to design optical switches or chemical and biological sensors as those are capable of detecting temperature, humidity, pressure, electric and magnetic fields, ions and solvents, biological materials, and hazardous materials. Apart from sensing applications, other device, display, and security applications are also discussed. This review summarizes the recent developments in soft material–based photonic crystals, including classification based on dimension and material, principles for design and fabrication, mechanism of color tuning, and their tunable structural color in responsiveness to various stimuli. Various techniques for creating soft material–based photonic crystals have been reviewed, including top-down and bottom-up approaches. Most of these techniques depend on self-assembly processes to accomplish ordering. Additionally, the present restrictions and prospective future paths in the domains of sensing and self-assemblies are also explored.