Abstract
We study the behavior of the phosphorescence and delayed fluorescence of the light-emitting polymer poly[9,9-di(ethylhexyl)fluorene] with different excitation intensities at low temperatures. The results indicate a limited number of potentially occupied energy sites (traps) for triplet-excited states. From analysis of temperature-dependent intensity measurements, we demonstrate the Gaussian distribution of these energy traps and determine an average trap depth of combined with a half-width of We also observe a redshift of the phosphorescence spectrum with increasing temperature, but no concomitant spectral narrowing.
- Received 11 July 2001
DOI:https://doi.org/10.1103/PhysRevB.65.073201
©2002 American Physical Society