Temperature dependence of exciton dynamics in poly(di-n-hexylsilane)

Abstract

We have investigated the temperature dependence of the time response of luminescence intensity in poly(di-$n$-hexylsilane) films in the range between 4 and 300 K and in solution at 4 and 295 K. In both samples, rise and decay times strongly depend on observed energy at 4 K. The rise time is about 100 ps at the peak energy. At about 110 K in films and at 295 K in solution, rise times become small and decay times become less dependent on energy with increasing temperature. In films at 295 K, decay times are independent of energy and rise times becomes less than 5 ps. These results are explained by the exciton dynamics governed by the competing processes of phonon scattering and radiative decay in disordered linear chains. It is found that the time response is more sensitive to temperature in films than in solution by the factor of 3. This difference is ascribed to the presence and the absence of interchain exciton transfer in films and in solution, respectively.