In this study, we decipher the charge transfer (CT) processes in donor-pyrene-acceptor (DPA) molecules via various time-resolved spectroscopic measurements. It has been challenging to unravel the ultrafast CT dynamics in DPA molecules because they exhibit an initial CT emission in the same spectral range as the locally excited (LE) emission. However, we finally observed the CT rate of ∼200 fs in DPA molecules from the time-resolved fluorescence anisotropy decay profiles. Our measurements allow us to suggest that the LE and CT states of DPA systems have isoenergetic potential surfaces and that the introduction of the acceptor to the pyrene moiety gives rise to strong electronic coupling between the LE and CT states. Therefore, we determined that this solvent-independent ultrafast CT occurs through the adiabatic potential energy surface and that the CT characteristics are enhanced in DPA compared to the donor-pyrene-donor system.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2020R1A5A1019141). We also give special thanks to Prof. Jong Seung Kim at Korea University for providing the samples studied in this work.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry