The role of coherence signifying concurrent electron-vibrational dynamics in complex natural and man-made systems is currently a subject of intense experimental and theoretical studies. Particularly, gaining control of this phenomenon is important for energy and charge transport when designing functional materials for various technologies, ranging from sensing, imaging, solar energy harvesting, to future optoelectronic devices. Using our non-adiabatic excited-state dynamics simulations (NA-ESMD) framework, we study ultrafast dynamics and exciton transport in several distinct molecular systems.  These simulations reveal a <b>ubiquitous pattern</b> in the evolution of photoexcitation spanning dynamics of multiple electronic states. Symmetries of the excited state wavefunctions define specific form of the derivative non-adiabatic coupling driving non-adiabatic qunatum transitions, which leads to a collective asymmetric vibrational excitation coupled to the electronic system. This promotes subsequent wave-like evolution of the excited state wavefunction preserving specific phase and amplitude relations across the ensemble of trajectories, facilitating efficient energy funneling. Proposed simple model explains appearance of coherent exciton-vibrational dynamics due to non-adiabatic quantum transitions, which is universal across multiple molecular systems studied.  Observed relationships between spatial extent/properties of electronic wavefunctions and resulting electronic functionalities allow us to understand and to potentially manipulate excited state dynamics and energy transfer pathways in a number of organic molecular materials.

Coherent exciton-vibrational dynamics and energy transfer in conjugated organics

254th National Meeting (2017)

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