| 초록 |
Colloidal self-assembly is a rapid and inexpensive fabrication method for photonic bandgap materials. However, typical close packed colloidal crystals have drawbacks such as difficulty in photonic bandgap tuning, and angle dependent Bragg diffraction which makes pure reflection color for broad viewing angle troublesome. In this study, we report reversible photonic bandgap tuning of colloidal crystals with enhanced viewing angle. We used electrically charged polystyrene particles to make crystalline colloidal arrays in aqueous medium. When the electric field was applied, crystal lattices were either compressed or relaxed due to electrophoretic movement of particles. As a result, photonic bandgap was reversibly shifted to over 100 nm spectral range when we applied ~ 2 V electric potential. Moreover, by incorporating carbon nanoparticles to the aqueous matrix, we enhanced scattering intensity of first order Bragg diffraction which gives us wider viewing angle of reflection color. |
