Temperature dependent dynamics of the excitonic photoluminescence in zinc oxide nanorods

The temporal dynamics of the exciton photoluminescence (PL) in ZnO nanorod samples was investigated experimentally as a function of temperature and excitation intensity. Excitonic photoluminescence is observed up to room temperature. The excitation dependence of the PL dynamics reveals a saturable non-radiative recombination center. Under high excitation conditions the time-resolved photoluminescence shows two components: the ZnO M-band which decays with a temperature independent sub-100 ps time constant, and the intrinsic exciton PL with a time constant of several 100 ps increasing with temperature. Exciton-exciton scattering effects are notably absent, which is attributed to the reduced polariton phase space resulting from the small nanorod diameter of 50 nm.