Temperature dependence of luminescence intensity and decay times in C-60 single crystal

Luminescence properties for C-60 single crystal, the temperature dependence of the luminescence spectra and decay kinetics were measured for a wide range of excitation energies. At low temperatures the emission spectra with well resolved structure were detected. There were not observed any changes in the luminescence spectra under different excitation energy. With careful measurements of the luminescence intensity as function of temperature we were able to detect the particularity on the curve at T similar to 250 K which corresponds to the phase transition in this material. Opposite to the case of C-60 films, the shape of the single crystal luminescence spectra also changes with temperature. The luminescence kinetic as function of temperature was investigated in nanosecond range. At temperatures T> 300 K the decay curve can be fitted by one exponent with t similar to 1 ns. When temperature decreased this component becomes non exponential and more slower. Thermostimulated current spectroscopy reveals the availability at least two traps for charged carriers.