Photophysics of PPV derivatives with varying conjugation lengths

Detailed Single-Molecule Spectroelectrochemical Studies of the Oxidation of Conjugated Polymers

“…On the basis of the current understanding of the electronic energy levels of conjugated polymers, to a first approximation, p ( E 1/2 ) and p ( E HOMO ) should be related to the distribution of conjugation length of such segments (i.e., redox units). A variety of factors (e.g., electron correlation effects, thermal disorder, and packing-induced torsion) limit the maximum effective conjugation length, − creating an energy-level accumulation effect in the low-energy edge of the HOMO band. This pile-up effect should lead to a narrow distribution of redox accessible states on the low potential edge of p ( E 1/2 ) and p ( E HOMO ).…”

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

“…As the degree of conjugation decreased, the PL and EL efficiencies increased. 255 This approach was readily adopted to prepare MEH-PPV precursors 23 but failed in the case of unsubstituted PPV (1). 256 Similar control of conjugation length has also been obtained by means of the precursor polymers 24, in which the xanthate groups could be selectively eliminated.…”

Spatial Confinement of Exciton Transfer and the Role of Conformational Order in Organic Nanoparticles

“…These single-molecule results on the MEH-PPVx series parallel the previously published ensemble measurements. 16,25 For MEH-PPV97 the narrow red-shifted fluorescence spectrum is highly suggestive of efficient energy migration to a small number of low energy chromophores. 1 Correspondingly, for MEH-PPV45 the single molecule fluorescence spectrum suggests very little energy migration.…”