Highly Efficient One-Photon Upconversion with Cooperative Enhancements of Photon and Phonon Absorption in Chlorophyll Plexciton Hybrids

We have demonstrated greatly enhanced light harvesting and one-photon upconversion in the plexcitonic hybrids of chlorophyll molecules strongly coupled to silver nanoparticles. The enhancement factors of the instantaneous and time-average upconversion intensity of the hybrids reached maxima of 36.2 and 28.5, respectively. Furthermore, the power and temperature dependences as well as the excitation and emission dynamics of upconversion were systematically investigated, revealing that highly efficient upconversion is predominantly attributable to the one-photon anti-Stokes process. The photon and phonon absorption processes are cooperatively enhanced by plexciton resonance. Additionally, coherent plexcitonic Rabi oscillations and plexciton-enhanced triplet–triplet annihilation are also discussed.