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Excitonic funneling in extended dendrimers with nonlinear and random potentials
Raychaudhuri1, Shapir, Chernyak
1Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Physical Review Letters
|September 16, 2000
Summary
We computed the mean first passage time for light-harvesting antennas, finding that nonlinear potentials and solvent fluctuations slow diffusion. At low temperatures, specific paths dominate the diffusion process.
Area of Science:
- Photophysics and exciton dynamics in artificial light-harvesting systems.
- Computational physics and statistical mechanics of disordered systems.
Background:
- Artificial treelike light-harvesting antennas, such as phenylacetylene dendrimers, are designed to mimic natural systems for efficient energy transfer.
- Understanding the diffusion dynamics of photoexcitations within these complex structures is crucial for optimizing their performance.
- The mean first passage time (MFPT) is a key metric for characterizing the efficiency of energy transport.
Purpose of the Study:
- To compute the MFPT for photoexcitations diffusing in a funneling potential within artificial treelike light-harvesting antennas.
- To investigate the influence of nonlinear potentials and solvent fluctuations on diffusion dynamics.
- To analytically study diffusion on a disordered Cayley tree with a linear potential.
Main Methods:
- Numerical computation of MFPT for photoexcitations in a funneling potential of phenylacetylene dendrimers.
- Analytical investigation of diffusion on a disordered Cayley tree with a linear potential.
- Analysis of the effects of potential nonlinearity and solvent fluctuations on diffusion rates.
Main Results:
- Nonlinearity of the funneling potential and slow solvent fluctuations significantly impede center-bound diffusion.
- An optimal antenna size, dependent on temperature, was identified beyond which diffusion slows considerably.
- A distinct low-temperature phase was predicted for diffusion on a disordered Cayley tree, where MFPT is governed by a few dominant pathways.
Conclusions:
- Realistic funneling potentials and solvent dynamics introduce complexities that can hinder energy transfer efficiency in artificial light-harvesting antennas.
- The observed diffusion behavior suggests a trade-off between antenna size and energy transport efficiency.
- The study highlights the importance of considering specific pathways in disordered systems at low temperatures for efficient energy transport.
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