The high PLQY values suggest that TPE-BBT could be a reliable PLQY standard for NIR-II materials. In addition, TPE-BBT exhibits absorption from 600 to 900 nm and fluorescence from 850 to 1500 nm, aligning with the typical uses of NIR-II materials. However, ensuring the consistency and reproducibility of nanoparticle preparation is challenging, and different laboratories may not achieve a fixed PLQY for TPE-BBT nanoparticles. Comparatively, simply dissolving TPE-BBT in its good solvents to prepare a solution sample would be better for a PLQY standard. However, for AIEgens, maintaining high brightness in the solution state is quite challenging. Fortunately, we can achieve this goal by utilizing the TICT effect. TICT is a common cause of quenching the fluorescence of NIR-II dyes. When the donor-acceptor (D-A) interaction of a dye molecule is too strong, the molecule will stabilize the charge-separated state in the excited state by twisting its structure (Figure ). This interferes with exciton recombination, thereby diminishing fluorescence emission. As a NIR-II emissive organic fluorophore, the D-A interaction of TPE-BBT is strong enough to induce a noticeable TICT effect. Therefore, we selected a series of good solvents with different polarities for TPE-BBT to study its solvent effect. Ideally, TPE-BBT would have sufficient NIR-II PL when dissolved in low-polarity organic solvents (Figure ). laser excitation, which is commonly used for NIR-II bioimaging (Figure ). In the low-polarity toluene, TPE-BBT has the highest PLQY (>6%). In solvents of medium polarity, TPE-BBT also shows good PLQY of approximately 4%-5%. In highly polar solvents such as DMSO, we could not measure a reliable PLQY, indicating that the integrating sphere cannot detect the brightness at this point.