Exciton diffusion in organic materials provides the operational basis for functioning of such devices as organic solar cells and light-emitting diodes. Here we track the exciton diffusion process in organic semiconductors in real time with a novel technique based on femtosecond photoinduced absorption spectroscopy. Using vacuum-deposited C70 layers as a model system, we demonstrate an extremely high diffusion coefficient of D≈3.5×10-3 cm2/s that originates from a surprisingly low energetic disorder of <5 meV. The experimental results are well described by the analytical model and supported by extensive Monte Carlo simulations. The proposed noninvasive time-of-flight technique is deemed as a powerful tool for further development of organic optoelectronic components, such as simple layered solar cells, light-emitting diodes, and electrically pumped lasers.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)