화학공학소재연구정보센터
Macromolecules, Vol.28, No.7, 2465-2471, 1995
Triplet Photophysics of Multichromophoric Molecules - A Study of Poly(N-Vinylcarbazole) and Meso-2,4-Dicarbazolylpentane in Fluid Solutions
Delayed luminescence and transient absorption experiments have been carried out on fluid solutions of poly(N-vinylcarbazole) (PVCz) and meso-2,4-dicarbazolylpentane (DCP) in benzene, cyclohexane, and 1,1-dimethylformamide (DMF). The delayed emission spectra of dilute solutions of DCP in all the solvents are similar and consist of excimeric delayed fluorescence (EDF) with a small contribution from monomeric delayed fluorescence. For PVCz in both benzene and DMF the delayed emission consists primarily of EDF at a delay of 1 mu s, but this signal decays away quickly leaving the excimeric phosphorescence band at longer delay times. The transient absorption spectra for DCP depend markedly upon the solvent. In benzene and cyclohexane the absorption is due to the carbazolyl triplet state, but in DMF absorbance bands due to the triplet and to radical cations and anions are found. Transient absorption spectra were also recorded for PVCz in benzene and DMF. Again, ionic species predominate in DMF and triplet states predominate in benzene, while the triplet excimer is present in both solutions. It is concluded that a conformation suitable for triplet excimer formation Can be achieved within PVCz polymeric coils but cannot be formed intramolecularly within DCP.