Ultrafast Energy Transfer Followed by Electron Transfer in a Polymeric Nanoantenna-Based Light Harvesting System

A polymeric nanoantenna-based light harvesting system is prospective because of it captures more number of photons by a multichromophoric donor and subsequently transfers its energy to the acceptor. Here, we have designed an aqueous solution-based polymeric nanoantenna, where conjugated polymer nanoparticles (donor) are attached with Au nanoparticle-capped porphyrin (acceptor)-encapsulated bovine serum albumin protein for both energy transfer and electron transfer processes. Ultrafast fluorescence upconversion and transient absorption spectroscopic studies reveal that the ultrafast energy transfer occurs from the conjugated polymer nanoparticle to porphyrin in 130 fs, followed by the electron transfer from porphyrin to Au nanoparticles in 70 ps after photoexcitation. Furthermore, the antenna effect of this light harvesting system is found to be 79 at the donor to acceptor ratio of 16:1. Analysis reveals that this polymeric nanoantenna opens up a new avenue for designing a highly efficient aqueous solution-based light harvesting system.