In TADF materials, the energy gap between S1 and T1 is sufficiently low (<0.2 eV) to enable endothermic up-conversion of triplet excitons into singlets via RISC at room temperature. For organic laser applications, RISC not only reduces the accumulation and annihilation of triplet excitons but potentially also generates radiative singlet excitons for SE, thus reducing the stimulated emission threshold. The first report of the use of a TADF material in light amplification employed ACRXTN in conjunction with the laser dye C545T in mCBP as a host matrix. The three-component system exhibited an ASE threshold (Eth) of 0.8 µJ/cm 2 compared to 1.2 µJ/cm 2 for a two-component system without ACRXTN. Nakanotani et al. reported the direct observation of ASE in the multi-resonant TADF (MR-TADF) emitter DABNA-2 doped in mCBP. Thanks to its high ΦPL (83% in 6 wt% doped films in mCBP), short prompt fluorescence lifetime τp (6 ns), and narrowband emission spectrum, DABNA-2 shows a large SE cross-section (σem) of 9.1 × 10 -17 cm 2 , and an Eth of 1.6 µJ/cm 2 . This result demonstrates that suitable TADF-type organic molecules can form a new category of ASE gain media for OSLs. Recently, Zhou et al. showed the influence of the RISC rate on the lasing efficiency from a TADF emitter 4CzTPN in doped polystyrene (PS) microspheres. With this TADF emitter, triplet excitons can continuously be converted to radiative singlet excitons through RISC, and the regenerated singlet excitons promote a population inversion in the S1 state. As the RISC is an endothermic process, the SE intensity of the 4CzTPN/PS microsphere gradually increased with increasing temperature from 100 K to 310 K. Recently, Fu et al. reported two difluoroboron based emitters DCzBF2 and DtCzBF2, both of which exhibited TADF and aggregation-induced emission (AIE) behavior. The microwire lasers with these two emitters showed emission peaks at 465 and 473 nm, and relatively low threshold energy of 3.8 and 17.0 μJ cm -2 , respectively. From these initial studies, the use of TADF materials seems to be a promising approach to reduce the detrimental effect of accumulated triplet excitons in OSL. Nevertheless, reports on the light amplification properties of such materials remain rare and further investigation of their photophysics is still needed. Pyrazine has been explored by our group as an acceptor moiety in donor-acceptor TADF emitter design and as a host for organic light-emitting diodes (OLEDs). We demonstrated that the sky-blue TADF emitter 4CzPz (Figure ), which exhibits weak TADF in 10 wt% doped films in 2,8-bis(diphenylphosphoryl)-dibenzo [b, d]thiophene (PPT) due to its moderately large ΔEST of 0.23 eV, and has a τd of 150 μs and a ΦPL of 75%. The device with 4CzPz showed sky-blue (λEL = 486 nm) emission with an EQEmax of 24.1%. In this work, we have designed two pyrazine-based TADF emitters 4tCzPz, and 4αCbPz, where four tert-butylcarbazoles (tCz) or α-carbazolines (αCb) are connected to the central pyrazine acceptor, and compare their performance to the previously reported TADF emitter 4CzPz, acting as a reference material.