We have measured the absorption, luminescence, luminescence excitation spectra, and time response of the luminescence intensity of poly(di-n-hexylsilane) (PDHS) film and of low-temperature glass of dilute PDHS solution at 2 K. It is found that the luminescence peak energies shift with the excitation energy below (Formula presented) for the film and below (Formula presented) for the glass, and that the rise and decay times of luminescence intensity at the peak energies are 70 and 300 ps, respectively, for the film, and 130 and 260 ps, respectively, for the glass. In order to explain these results, numerical diagonalization of the one-dimensional Frenkel exciton Hamiltonian with disorder is carried out, and the luminescent process is formulated with the assumption that the exciton does not change the site by phonon scattering. We estimate the transition-dipole moment to be (Formula presented) for the film and (Formula presented) for the glass and the transition constant to be (Formula presented) for the film and (Formula presented) for the glass. We discuss the role of hidden structures at the low-lying exciton states that appear in the site representation of exciton wave functions. The hidden structure correlates the microscopic picture with the phenomenological segment model. It is found that the long-range dipole-dipole interaction contributes to the long luminescence rise time.
|Number of pages||11|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1998 Jan 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics