Fabrications and Characterizations of Crystalline and Complex-index Materials Doped Hyperuniform Disordered Photonic Materials

Abstract

This thesis investigates novel optical and physical properties of photonic crystals depending on structures and doping materials. Photonic crystals are made of polymers, colloids and organic/inorganic composites with crystalline or quasi-amorphous photonic structures. We made hyperuniform disordered photonic structures (HDPSs) with short-range correlations that may solve the problems of crystalline photonic crystals exhibiting anisotropic properties. Furthermore, optical properties of HDPSs were improved by adding complex-index materials at the dopant level. These results are promising for practical applications of photonic crystals. In chapter 1, overview and fabrication of photonic crystals are described. Furthermore, fabrication methods of HDPSs having short-range correlations are explained and their meaning is described. Also, optical properties improved by combining of structural colors and pigmentary colors. The meaning and necessity of this study are described. In chapter 2, fabrication of ultrahigh molecular weight brush block copolymer (BBCP) (PNB-g-PS)-b-(PNB-g-PVP) based 1-dimensional photonic crystals is described. BBCPs are effective materials to form lamellar structures through annealing due to low entanglement. The periodic structures of BBCPs could be rapidly formed because the repulsive force between brush groups decrease entanglement of polymer chains. Also, refractive index contrast was increased by selectively infiltrated 11-mercaptoundeconoic acid capped Au nanoparticles into PVP layers through hydrogen bonding. In chapter 3, we fabricate hyperuniform disordered photonic structures (HDPSs) having short-range correlations between nanoparticles by adjusting concentration and polydispersity of nanoparticles. HDPSs show angle-independent structural colors due to isotropic nature whereas crystalline photonic crystals show angle-dependent colors. However, reflectivity and color purity decrease by incoherent scattering. We solve this problem and increased reflectivity by adding complex-index materials which optical bandgap match with photonic bandgap of HDPS. This phenomenon results from resonant interferences and greatly effective way to enhance optical properties of HDPSs. In chapter 4, HDPSs captured photonic materials fabrication method was suggested. Nanoparticles dispersed photocurable resins were used for hyperuniform disordered photonic gels (HDPGs). HDPGs maintain short-range correlations of nanoparticles and the storage is easy at ambient conditions. Complex-index HDPGs also show high reflectivity and broad color expression range compared to pure HDPGs.