화학공학소재연구정보센터
Polymer, Vol.49, No.8, 2077-2084, 2008
Theoretical studies of the electronic structures and optical properties of stable blue-emitting polymer based on 4H-cyclopenta-[def]-phenanthrene
Geometries, ionization potentials (IPs), electron affinities (EAs) and optical properties of two series of pi-conjugated oligomers (2,6-(4,4-bis(2-ethylthexyl)-4H-cyclopenta-[def]-phenanthrene))(n) CPPn (2,6-(4,4-bis(2-ethylthexyl)-8,9-dihydro-4H-cyclopenta-[def]-phenanthren e))(n) HCPPn (n = 1-4) were studied theoretically. The ground and the excited state geometries were optimized by B3LYP and CIS methods with 6-31G* basis sets, respectively. The absorption and the emission spectra were calculated by TD-B3LYP method. The lowest-lying absorption is assigned to pi ->pi* transition, and the fluorescence can be described as originating from the (1)[pi pi*] excited state. IPs, EAs, H-L gaps, absorption and emission properties of PCPP (n = infinity) and PHCPP (n = infinity) were obtained by extrapolation method. The fact that the lowest-lying absorption and the emission of PCPP are blue-shifted compared with those of PHCPP, can be interpreted by the smaller effective repeating units of PCPP. The extra absorption band at 289 nm of PCPP is contributed by the pi ->pi* transition involving the extra pi-conjugation C=C bond.