Poly p-Phenylene Vinylene Homopolymers with Electron-Withdrawing and Donating Substituents

5 Poly(p-Phenylene Vinylene) Homopolymers with Electron-Withdrawing and Donating Substituents 

SCHEME 2.14 Tuning the energy levels of PPV by introducing pendant charge-transporting units. The HOMO defined as the -/P value (determined from the UPS experiments) and the LUMO was deduced by adding the optical gap to the HOMO value. 

In a similar approach, the HOMO level of PPV was controlled by the introduction of a dialkylamino donor group (polymer 64) [120] (Chart 2.12). The dialkylamino groups render 

The recently synthesized PPV 68, in which the oxadiazole group is separated from the PPV backbone by an oxygen atom, is a very soluble material with optical band gap of 2.36 eV and yellowish-orange emission color (chromaticity coordinates by the Commission Internationale de l Eclairage, CIE a 0.50, y = 0.47 591 nm) [124]. An extremely high- 

Using CPR, Burn and coworkers introduced several electron-accepting moieties such as p-nitrostyryl (69 [125]) and methylsulfonyl-phenyl (70 [126]) groups as substituents in the PPV backbone. However, essentially no difference in EL performance (maximum QE 0.01% for ITO/polymer/Al) was found between polymers 70 and 71 and the authors concluded that the methylsulfonyl group in the pendant phenyl ring does not facilitate electron injection (Chart 2.13). 

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