Fig. 4: Demonstration for necessity of dynamic coupling.

a Analysis of excitation spectra of PY−CzA. The excitation spectrum of the complex emission was measured at 470 nm (L_C; blue solid line). The excitation spectrum of phosphorescence was measured at 595 nm with a delay of 10 ms (P_G; red solid line). The excitation spectrum of the dynamic complex component was obtained by measuring the excitation spectrum of CzA crystals (L_C,D; line with blue circles). The excitation spectrum of the static complex component was obtained by subtracting the dynamic component from the excitation spectrum of the total complex emission (L_C,S; line with green circles). The excitation spectrum of PY−PMMA was attached for reference (gray line). Inset: the difference between dynamic and static complexes. b Excitation-phosphorescence mapping of PY−CzA with a delay of 1 (left) and 10 ms (right). The upper insets: the delayed PL spectra excited at 360 nm and 380 nm. P_G appeared through dynamic coupling when PY−CzA was excited at 360 nm but disappeared when static complex was excited at 380 nm. c Pressure-dependent PL spectra of PY−BrCzA excited at 355 nm. d Pressure-dependent X-ray diffraction patterns of PY−BrCzA crystals. The diffraction peak of (004) crystal plane was denoted. e The variations in the intensities of L_C and P_G, along with the interplanar spacing of (004) crystal plane, as external pressure increased. f Rate constants of radiative and non-radiative decay from S_C state within PY−BrCzA complex under different pressure. g Schematic diagram for different impact of static (left) and dynamic (right) coupling on RTP (P_G). In static coupling, the static complex was already formed in the ground state. Upon excitation to S_C and subsequent ISC to T_C, the static complex remained coupled and decayed back to the ground state, exhibiting L_C emission. In dynamic coupling, the dynamic complex was formed after excitation to the excited state. After undergoing ISC process to T_C, the dynamic complex dissociated and facilitated the transfer of excitons to T_G. Thus, the excitons decayed from T_G, exhibiting P_G emission.