Reductive photopatterning of phenylene-vinylene-based polymers

Abstract

Photochemical methods were developed to obtain a variation of the refractive index in aromatic polymer surfaces and a change in the photoluminescence characteristics of phenylenevinylene-based polymers. Films of aromatic polymers, among them polystyrene (PS), poly(2-vinylnaphthalene) (PVN) and derivatives of poly(p-phenylene-vinylene) (PPV) were UV irradiated in the presence of gaseous hydrazine (N2H4). The photoreaction led to a strong reduction of the refractive index of the polymers due to a hydrogenation of the aromatic units. In the case of PPV, we observed reductive photobleaching. This new technique was employed to produce photogenerated patterns in PPV. The results are compared to oxidative bleaching.

Tuning the Electroluminescence Color in Polymer Light-Emitting Devices Using the Thiol-Ene Photoreaction

“…[16] We have shown, that a photoreaction with hydrazine can be used to selectively saturate (hydrogenate) the vinylene groups in a poly(p-phenylenevinylene) (PPV) chain, leaving the aromatic units intact up to long UV exposure times. [17] Exploiting this chemical selectivity, we have shown that the total electroluminescence (EL) color of thin films, consisting of a poly-aromatic (blue-emitting) host and a (lower-bandgap) guest polymer containing vinylene units, can be changed from the emission color of the guest to Laterally patterning the emission color of polymer light-emitting devices is one of the current technological challenges for their commercialization. Photopatterning is one of the most convenient approaches for the production of closely spaced, differently colored pixels, other than direct-writing approaches such as ink-jet printing.…”