Excimer formation and charge carrier photogeneration in solid polymers

Synthesis and spectral investigation of alkyl methacrylates with halogenated carbazolyl pendant groups for photonics applications

“…On the other hand, it is known17 that excimers do not exist in macromolecules of such a type. Moreover, we did not observe the excimer fluorescence in similar macromolecules but without Cl or Br 13, 15, 20–23. Therefore, we can conclude that the emission of polymers under study is mainly determined by impurity centers.…”

Investigation of purity and fluorescence of poly[N6-(9H-carbazol-9-ylcarbonyl)-L-Lysine] preparations

“…It is, however, relevant to compare the present fluorescence spectra with, on one hand, those of the homopolymers poly(Ar-vinyl-9H-carbazole) (PVCz)4,28-30 and poly(Nvinyl-5H-benzo [5]carbazole) (PV5BCz)28,31 and, on the other hand, those of copolymers of IV-vinyl-9H-carbazole (VCz) with 7V-vinyl-5H-benzo[0]carbazole (V5BCz). 30,32,33 For PVCz the long-wavelength (Xmax ~420 nm) emission was attributed to an intrachain excimer state4,28,30 and the shorter wavelength (Xmax ~380 nm) emission was attributed to either a normal carbazole molecular flourescence4,30 or a second excimer emission.4,28 Depending on the polymerization conditions (radical or cationic) different fluorescence spectra were obtained for PV5BCz. For the radical polymers the spectra were composed of a second excimer fluorescence at the shorter wavelength (X = 443 nm) and a sandwich-like excimer fluorescence at the longer wavelength (X = 491 nm).28,31 The cationic polymers did not show the second excimer fluorescence, but a monomer-like structured fluorescence, at the shorter wavelength, although it did show the sandwich-like excimer fluorescence at the longer wavelength.…”

“…30,32,33 In dioxane solution the host PVCz (monomer (A = 370 nm) plus excimer (A = 410 nm) type) fluorescence was quenched by V5BCz guest units and the guest emission appeared. It is, however, relevant to compare the present fluorescence spectra with, on one hand, those of the homopolymers poly(N-vinyl-9H-carbazole) ( P V C Z )~,~~-~O and poly(Nvinyl-5H-benzo[b]carbazole) ( P V~B C Z )~~,~~ and, on the other hand, those of copolymers of N-vinyl-9H-carbazole (VCz) with N-vinyl-5H-benzo[ blcarbazole For PVCz the long-wavelength ( A, , -420 nm) emission was attributed to an intrachain excimer state4,28,30 and the shorter wavelength (Amm -380 nm) emission was attributed to either a normal carbazole molecular floure~cence~~~~ or a second excimer e m i s~i o n .~!~~ Depending on the polymerization conditions (radical or cationic) different fluorescence spectra were obtained for PV5BCz.…”

Dissociation of electron-hole pairs interacting with triplet excitons in amorphous molecular semiconductors

“…Light of wavelength l 2 365 +2 nm is close to the red limit of PEPC absorption, where eective photogeneration of triplet excitons takes place. 13 Light intensities were varied within the limits I 1 0X5±70 W m À 2 and I 2 0X01±0X2 W m À 2 by ®lters. Homogeneous volume photogeneration of EHPs was ensured 10Y11 during sample illumination with light of wavelength l 1 and quasihomogeneous volume photogeneration of triplet excitons took place 14 during sample illumination with light of wavelength l 2 under our experimental conditions.…”