The energy differences between T1 H and T1 L approximated from the onsets of the respective phosphorescence spectra are 0.36 eV, and 0.31 eV for TDMACPhCor, and TPXZPhCor, respectively (Figure ). With a potential view to assessing these materials in OLEDs, we explored the photophysics in doped films in mCP as this host has a T1 energy of ~3.0 eV, 68 thus excitons would be confined onto the RTP emitters. The optimized doping concentrations of TCzPhCor, TDMACPhCor, and TPXZPhCor are 1 wt%, 7 wt%, and 15 wt%, respectively, where the ΦPL values are 37.2%, 32.1%, and 42.5%, respectively. The steady-state PL spectra of the three emitters in air and vacuum at 298 K show broad and structureless emission at lPL of 465 nm, 475 nm, and 530 nm (Figures , top), with tPL of 6.5 ns, 19.8 ns and 30.7 ns, for TCzPhCor, TDMACPhCor and TPXZPhCor, respectively (Figure ). Similar to the result recorded in PMMA, TCzPhCor in mCP exhibits RTP at 588 nm with τPh of 293.7 ms (Figure ), which originates mostly from T1 L that is localized on the TPhCor core. The unchanged phosphorescence spectra as a function of temperature are consistent with a single origin of the phosphorescence (Figure , bottom). For TDMACPhCor, dual RTP emission from T1 H and T1 L was observed, centered at 480 nm and 585 nm Figure , bottom) with associated tPh of 96.8 ms and 343.3 ms (Figure ), respectively. As the temperature decreases, the high-energy phosphorescence from T1 H decreases in intensity as it can no longer be efficiently populated. For TPXZPhCor, the emission at 528 nm is dominated by the RTP from T1 H (Figure , bottom), with a τPh of 82.6 ms (Figure ). This is reflected by a significant change in the spectral profile as a function of temperature (Figures and). The FRTP of TCzPhCor, TDMACPhCor and TPXZPhCor in mCP are 2.6%, 2.7%, and 18.0%, respectively, which are much higher than those measured in 1 wt% doped PMMA films (0.1% for TCzPhCor, 0.3% for TDMACPhCor and 10.0% for TPXZPhCor, respectively) (Figure ). This divergence in FRTP recorded in mCP and PMMA results from different host-guest interactions, which provides a window into an effective strategy to regulate the T1 H and T1 L excitonic coupling. TPXZPhCor doped mCP film possesses the highest RTP FPL (17.8%), higher than that of the 1 wt% doped film (RTP FPL = 10.2%) (Figures ). The observed aggregation-induced phosphorescence enhancement is hypothesized to originate from the twisted geometry, which disfavors unwanted intermolecular π-π interactions (Figure ). Both 1 wt% and 30 wt% TPXZPhCor doped mCP films exhibit similar temperature-dependent phosphorescence behavior to the 15 wt% doped sample. As temperature decreases, there is a red shift of the phosphorescence, reflected in the temperaturedependent phosphorescence afterglows (Figures ) and evolution in the CIE coordinates (Figures ). The photophysical investigation at these two doping concentrations indicates that aggregation has negligible influences on the T1 H and T1 L phosphorescence spectra, which implies that the phosphorescence occurs from monomolecular species and not aggregates.