The three abovementioned HLCT emitters showed similar absorption bands in the ultraviolet and blue spectral ranges in dilute toluene solutions. A broad, featureless absorption band was observed at around 360-500 nm with peak at 410  413 nm, which is assigned to the intramolecular charge transfer (ICT) absorption associated with the electron transfer from the fluorene to benzothiadiazole (Fig. ). Noteworthily, the molar absorption coefficient (ε > 2×10 4 L•mol -1 cm -1 ) are significantly higher than those of TADF emitters with TICT characters . In contrast, the steady-state photoluminescence (PL) spectra of these HLCT emitters show an unstructured emission band from 480 to 640 nm centered at approximately 520 nm. Thanks to the CT character of HLCT state, the overlaps between the absorption and emission spectra are small (free reabsorption feature). This results in large Stokes shift (>100 nm), which is a prerequisite for high-performance scintillators.