Directed Energy Transfer

摘要

In the field of optical energy harvesting it has long been known that the efficient capture of radiation by suitably designed absorbers is by no means the sole criterion for an effective collection system. The optical energy acquired by an absorbing medium is of little value at its absorption site; useful devices require that the energy rapidly and non-diffusively relocates to traps or reaction centers. Storage is then achieved by driving charge separation or another more complex reaction. The principles that operate over the crucial mechanisms for inter-site energy transport are now well understood, and materials can be engineered to expedite and control an optimally directed, multi-step flow of energy. In this paper the salient principles drawn from nanophotonics, fluorescence spectroscopy, molecular electronic structure and nonlinear optics are exhibited with reference to a number of recently devised energy harvesting materials and systems, prominently featuring dendrimeric organic polymers. It is also shown how the elementary transfer mechanism can be tailored to more efficiently direct the flow of excitation energy.