Oligomers luminescent

We have studied two types of polymers that both belong to the second case those in which luminescent chromophores (typically K-coujugatcd oligomers) are separated by higher-energy-gap blocks (see Fig. 16-1 a) and those in which the chromophores are linked to each other in a non-coplanar way (sec Fig. 16-lb). 

Starting from the assumption that the geometry relaxation after excitation is of primary importance with respect to the luminescence response, we decided to employ a solid polymer matrix to suppress conformational changes of the oligomers. For the measurements, dilute blends with polysulfone as the transparent host matrix were prepared. In Figure 16-13, the PL decay curves for the two cyano compounds in both chloroform and polysulfone are presented, as are the PL spectra of Ooct-OPV5-CN in chloroform and polysulfone [69J. 

Rawashdeh-Omary, M.A., Omary, M.A., Patterson, H.H. and Fackler, J.P. Jr (2001) Excited-state interactions for [Au(CN)2 ]n and [Ag(CN)2 ]n oligomers in solution. Formation of luminescent gold-gold bonded excimers and exciplexes./oumol of the American Chemical Society, 123, 11237-11247. 

Poly(2,5-pyridyl) commonly know as poly(pyridine) has been the subject of considerable research effort as it luminesces in the blue region of the spectrum and may have uses in light emitting diodes (LEDs). Vaschetto and co-workers [103] reported a series of calculations on the molecule and its oligomers. The calculations included both the B3LYP and B3P88 density functions, Hartree-Fock calculations and a periodic solid-state DFT calculation using linear muffin tintype orbitals (LMTO). 

Rawashdeh-Omary, M. A. Omary, M. A. Patterson, H. H. Fackler, J. P. Excited-State Interactions for [AuJCNjjIn and [AgJCNjj"] Oligomers in Solution. Formation of Luminescent Gold-Gold Bonded Excimers and Exciplexes. J. Am. Chem. Soc. 2001, 123, 11237-11247. 

Device motivation for interface studies, and Optical absorption and emission in conjugated oligomers and polymers. The principles of device physics of metal insulator field-effect transistors (MISFETs) and light emitting diodes (LEDs) are oudined mainly as motivation for the contents of the chapters which follow, but also to point out certain features relevant to developing an understanding of the nature of the polymer-metal interface (chapters 5 and 6). The basic principles of electro-luminescence are reviewed here, at the level consistent with the aims of this work. 

Finally, it should be stressed that photoluminescence has usually a larger quantum yield in solution than in the solid state27. In the latter case, inter-chain interactions appear to quench the luminescence properties through a mechanism that is not fully understood yet. In this context, it is, however, useful to note that the possibility that the polaron-excitons evolve into excimers28 is ruled out by the absence of Stokes shifts in good-quality PPV oligomer and polymer samples14. 

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