Temperature dependence of resonance energy transfer in DCM doped anthracene nanoaggregates

Abstract

The efficiency of the organic semiconductors in optoelectronic devices is highly dependent upon the excitonic diffusion properties. Again the exciton diffusion properties as well as device performance may be affected by the variation of ambient temperature. Thus it is essential to know the temperature variation effect upon the exciton diffusion properties of an organic semiconductor material. Herein the same understanding has been obtained by observing the energy transfer efficiency in the 2–70 °C temperature range with DCM doped anthracene nanoaggregates. The highly efficient energy transfer process observed in these doped nanoaggregates is established to be diffusion controlled and thus the energy transfer efficiency is directly related to the exciton diffusion property of the host matrix. The present results show significant decrease in energy transfer efficiency upon enhancement in sample temperature. This observation indicates slow exciton diffusion process at higher sample temperature. It contradicts previously reported opposite trend which has been explained by involvement of thermally activated hopping mechanism in organic semiconductor samples. The opposite trend observed here indicate presence of some dominating negative effect in this experimental temperature range. It is proposed that, the temperature dependent enhancement in intermolecular separation as the main possible reason for slower exciton diffusion process and less efficient resonance energy transfer in doped anthracene nanoaggregates.