We have measured the time response of photoluminescence intensity in poly(di-n-hexylsilane) films at 2 K with excitation densities from 1.2 × 1017 to 1.1 × 1019 excitons cm-3. At the highest density, the photoluminescence has a rise rime of 1.4 ps, which is ascribed to the exciton-exciton scattering time between initially photogenerated excitons. The inverse of rise times are sublinear to the excitation densities. The decay profiles are explained by the exciton-exciton annihilation with a rate constant of (1.0±0.5) × 10-8 cm3 s-1. These processes are discussed in terms of exciton wave functions obtained by the one-dimensional Frenkel exciton model with disorder. We propose directional relaxation of excitons toward interacting points between different polymer chains as a mechanism for the efficient exciton-exciton annihilation.
|Number of pages||9|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2001 Sep 15|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics