Optical Properties of Cyclic Amine Type Dyes, and Their Electronic Band Structures with Molecular Microstructure

Three different cyclic amine dyes, 9-(2-chlorophenyl)-9H-carbazole (CPCz; C18H12ClN), 10-(2-chlorophenyl)-10H-phenoxazine (CPPo; C18H12ClNO), and 10-(2-chlorophenyl)-10H-phenothiazine (CPPt; C18H12ClNS), were synthesized to systematically investigate their optical properties and electronic band structures with molecular microstructure. By the insertion of oxygen or sulfur atom into carbazole moiety, the absorption and photoluminescence (PL) spectra showed bathochromic shift, and the Stoke's shift was increased. Ionization potential of CPCz was measured as 5.75eV, on the other hand, CPPo and CPPt showed their ionization potentials of 5.37 and 5.39eV, respectively. The minute difference in chemical structure such as insertion of oxygen or sulfur atom caused huge change of optical property and electronic band structure.