Tuning superposition of multiple Fano interferences for efficient plasmon resonance energy transfer to the assembled...

Plasmon-exciton Fano interference provides an efficient channel for coherent energy transfer, and the plasmon resonance energy transfer (PRET) peak is usually observed around the Fano dip at the exciton resonance. In this work, we achieve tunable multiple Fano interferences and multichannel PRET by strategically coupling five excitonic resonances (labeled as M, D_h, D_j, H, and J) of assembled IR806 molecules with Au nanobipyramids and nanorods (AuNBPs and AuNRs, respectively). Notably, owing to orientation-dependent molecule-plasmon coupling in the IR806/AuNBP hybrids, we observe two PRET peaks with opposite signs of Fano factor $q$ . One PRET peak remains fixed near the J-aggregate exciton resonance at ~900 nm, whereas the other is located around the plasmon resonance and tuned from 710 to 920 nm. The total PRET reaches a maximum when the two PRET peaks are tuned into spectral overlap. Furthermore, our newly developed semiclassical model quantitatively reproduces these features, which reveals that PRET enhancement arises from the superposition of multiple Fano interferences. These findings provide a novel strategy to enhance the efficiency and tunability of the PRET, opening avenues for advanced applications in ultrafast optical information processing and highly sensitive photodetectors.