The transient PL decay spectra disclose the S-enantiomers in toluene solutions experience double exponential decay processes under nitrogen with short mean PL lifetimes of 5.5-7.2 ns. Apparent delayed components with long lifetimes of 24.3-28.4 ns are observed under nitrogen, but the delayed components become weak with lifetimes reduced to 6.2-6.8 ns under air (Fig. , Supplementary Fig. and Supplementary Table ), indicative of the participation of triplet excited states in radiative decay process. In neat films, they show short mean PL lifetimes of 3.0-4.1 ns with decreased but discernable delayed components. The lifetimes of delayed components are shortened to 5.2-7.6 ns under nitrogen, but get slightly prolonged by increasing temperature from 77 to 300 K, as revealed by the temperature-dependent transient PL decay spectra (Fig. and Supplementary Fig. ). Similar trend is also observed for these materials in doped films (Supplementary Table and). Compared to the delayed lifetimes of up to microsecond level of typical TADF materials, the delayed lifetimes of these materials are apparently too short. To further understand the working mechanism of photophysical property, the fluorescence and phosphorescence spectra of the neat films of S-enantiomers are collected at 77 K to calculate S1-T1 energy splitting (∆EST) (Fig. and Supplementary Fig. ). Interestingly, each S-enantiomer shows one fluorescence peak but two phosphorescence peaks, and the short-wavelength phosphorescence peak is red-shifted by ~30 nm relative to the fluorescence peak. For example, the phosphorescence spectrum of S-BNPCN-o-CP in neat film has two peaks at 448 and 531 nm, with different lifetimes of 117 and 193 ms, respectively. In consideration of the extraordinarily short delayed lifetimes of these materials, this short-wavelength phosphorescence peak at 448 nm is deduced to be associated with high-lying triplet excited states, which undergo hRISC process to convert to S1 state, while the long-wavelength peak comes from T1 state. Thus, the ∆ESTs, calculated from the fluorescence peak and long-wavelength phosphorescence peak, are 0.52-0.67 eV for S-enantiomers in neat films. Similar phenomena are observed for their doped films in PPF host and the ∆ESTs are calculated as 0.46-0.56 eV (Fig. and Supplementary Fig. ). These findings disclose that the typical TADF is absent in these materials, and the short delayed components should be induced by hRISC process , which is in good agreement with the theoretical calculation results.