A very low lasing threshold of DABNA derivatives with DFB structures

For elucidating the potential of the light amplification properties of thermally activated delayed fluorescence (TADF) materials, distributed feedback (DFB) laser devices using DABNA derivatives having a multiple-resonance effect were fabricated. We demonstrated a very low lasing threshold of 0.27 μJ cm⁻¹, which is the best performance in TADF materials, for 6 wt%-DABNA-2 doped in an mCBP host layer combined with a mixed-order DFB structure. Furthermore, by focusing on the photophysical properties of the aggregated states of DABNA derivatives, advanced light amplification architectures composed of dual DABNA derivatives were examined. Consequently, the DABNA-based films also provided remarkably low lasing thresholds at high concentrations.