@article{DeviAlSutiDoscheetal.2008,
  author    = {Devi, Lekshmi Sudha and Al-Suti, Mohammed K. and Dosche, Carsten and Khan, Muhammad S. and Friend, Richard H. and K{\"o}hler, Anna},
  title     = {Triplet energy transfer in conjugated polymers : I. Experimental investigation of a weakly disordered compound},
  year      = {2008},
  abstract  = {Efficient triplet exciton emission has allowed improved operation of organic light-emitting diodes (LEDs). To enhance the device performance, it is necessary to understand what governs the motion of triplet excitons through the organic semiconductor. Here, we have investigated triplet diffusion using a model compound that has weak energetic disorder. The Dexter-type triplet energy transfer is found to be thermally activated down to a transition temperature T- T, below which the transfer rate is only weakly temperature dependent. We show that above the transition temperature, Dexter energy transfer can be described within the framework of Marcus theory. We suggest that below T-T, the nature of the transfer changes from phonon-assisted hopping to quantum-mechanical tunneling. The lower electron-phonon coupling and higher electronic coupling in the polymer compared to the monomer results in an enhanced triplet diffusion rate.},
  language  = {en}
}
@article{EvansDeviMaketal.2006,
  author    = {Evans, Nicholas R. and Devi, Lekshmi Sudha and Mak, Chris S. K. and Watkins, Scott E. and Pascu, Sofia I. and K{\"o}hler, Anna and Friend, Richard H. and Williams, Charlotte K. and Holmes, Andrew B.},
  title     = {Triplet energy back transfer in conjugated polymers with pendant phosphorescent iridium complexes},
  issn      = {0002-7863},
  doi       = {10.1021/Ja0584267},
  year      = {2006},
  abstract  = {The nature of Dexter triplet energy transfer between bonded systems of a red phosphorescent iridium complex 13 and a conjugated polymer, polyfluorene, has been investigated in electrophosphorescent organic light-emitting diodes. Red- emitting phosphorescent iridium complexes based on the [Ir(btp)2(acac)]fragment (where btp is 2-(2 '- benzo[b]thienyl)pyridinato and acac is acetylacetonate) have been attached either directly (spacerless) or through a - (CH2)(8)-chain (octamethylene-tethered) at the 9-position of a 9-octylfluorene host. The resulting dibromo- functionalized spacerless (8) or octamethylene-tethered (12) fluorene monomers were chain extended by Suzuki polycondensations using the bis(boronate)-terminated fluorene macromonomers 16 in the presence of end-capping chlorobenzene solvent to produce the statistical spacerless (17) and octamethylene-tethered ( 18) copolymers containing an even dispersion of the pendant phosphorescent fragments. The spacerless monomer 12 adopts a face-to-face conformation with a separation of only 3.6 angstrom between the iridium complex and fluorenyl group, as shown by X-ray analysis of a single crystal, and this facilitates intramolecular triplet energy transfer in the spacerless copolymers 17. The photo- and electroluminescence efficiencies of the octamethylene-tethered copolymers 18 are double those of the spacerless copolymers 17, and this is consistent with suppression of the back transfer of triplets from the red phosphorescent iridium complex to the polyfluorene backbone in 18. The incorporation of a -(CH2)(8)- chain between the polymer host and phosphorescent guest is thus an important design principle for achieving higher efficiencies in those electrophosphorescent organic light-emitting diodes for which the triplet energy levels of the host and guest are similar},
  language  = {en}
}
@article{HayerKhanFriendetal.2005,
  author    = {Hayer, Anna and Khan, A. L. T. and Friend, Richard H. and K{\"o}hler, Anna},
  title     = {Morphology dependence of the triplet excited state formation and absorption in polyfluorene},
  year      = {2005},
  language  = {en}
}
@article{MakHayerPascuetal.2005,
  author    = {Mak, Chris S. K. and Hayer, Anna and Pascu, S. I. and Watkins, Scott E. and Holmes, Andrew B. and K{\"o}hler, Anna and Friend, Richard H.},
  title     = {Blue-to-green electrophosphorescence of iridium-based cyclometallated materials.},
  issn      = {0022-4936},
  doi       = {10.1039/b508695gb70},
  year      = {2005},
  language  = {en}
}
@article{SandeeWilliamsEvansetal.2004,
  author    = {Sandee, A. J. and Williams, Charlotte K. and Evans, N. R. and Davies, J. E. and Boothby, C. E. and K{\"o}hler, Anna and Friend, Richard H. and Holmes, Andrew B.},
  title     = {Solution-processible conjugated electrophosphorescent polymers},
  year      = {2004},
  language  = {en}
}
@article{WilsonChawdhuryAlMandharyetal.2001,
  author    = {Wilson, J. S. and Chawdhury, Nazia and Al-Mandhary, Muna R. A. and Younus, M. and Khan, Muhammad S. and Raithby, Paul R. and Friend, Richard H.},
  title     = {The energy gap law for triplet States in Pt-containing conjugated polymers and monomers},
  year      = {2001},
  language  = {en}
}