We report on picosecond time resolved photoluminescence measurements in poly(p-phenylene vinylene) (PPV) films of thickness which exceeds the penetration depth of the exciting laser, irradiated by laser in air. The photoluminescence (PL) intensity increases during the irradiation process despite the increasing density of photo-oxidation induced carbonyl groups, usually acting as quenching centers. We study the PL enhancement and the dynamics of the PL decay for different irradiation conditions and different sample thicknesses. The PL decay surprisingly shows a reduced importance of defects trapping as the defect concentration increases, thus explaining the PL enhancement. We explain our results in terms of a chain shortening due to carbonyl incorporation and formation of an energy profile that extends and migrates into the film, enabling efficient spectral diffusion of excited carriers into nondegraded PPV segments by Förster energy transfer.

Defect-assisted photoluminescence intensity enhancement in poly(p-phenylene vinylene) films probed by time-resolved photoluminescence

ANNI, Marco;GIGLI, Giuseppe;CINGOLANI, Roberto;
2003

Abstract

We report on picosecond time resolved photoluminescence measurements in poly(p-phenylene vinylene) (PPV) films of thickness which exceeds the penetration depth of the exciting laser, irradiated by laser in air. The photoluminescence (PL) intensity increases during the irradiation process despite the increasing density of photo-oxidation induced carbonyl groups, usually acting as quenching centers. We study the PL enhancement and the dynamics of the PL decay for different irradiation conditions and different sample thicknesses. The PL decay surprisingly shows a reduced importance of defects trapping as the defect concentration increases, thus explaining the PL enhancement. We explain our results in terms of a chain shortening due to carbonyl incorporation and formation of an energy profile that extends and migrates into the film, enabling efficient spectral diffusion of excited carriers into nondegraded PPV segments by Förster energy transfer.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11587/108998
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 6
social impact