Enhanced energy transfer efficiency upon confining rhodamine B into zeolitic imidazolate frameworks

Enhancing the utilization of absorbed light is essential for enhancing the efficiency of solar energy conversion via artificial photosynthesis. In this work, we report the successful incorporation of Rhodamine B (RhB) into the pore of ZIF-8 (ZIF = zeolitic imidazolate framework) and the efficient energy transfer process from RhB to Co-doped ZIF-8. Using transient absorption spectroscopy, we show that energy transfer only occurs from RhB (donor) to Co center (acceptor) when RhB is confined into the ZIF-8 structure, which is in stark contrast to the system based on the physical mixture of RhB with Co-doped ZIF-8, where negligible energy transfer was observed. In addition, energy transfer efficiency increases with the concentration of Co and reaches a plateau when the molar ratio of Co to RhB reaches 32. These results suggest that RhB confined in the ZIF-8 structure is essential for energy transfer to occur, and energy transfer efficiency can be controlled by tuning the concentration of acceptors.