Rational design of two-photon near-infrared TADF emitters via acceptor modulation: A theoretical investigation.

Two-photon absorption (TPA) combined with thermally activated delayed fluorescence (TADF) molecular systems hold great promise for organic optoelectronics and bioimaging due to their high electroluminescence efficiency and nonlinear optical properties. However, current TPA-TADF emitters suffer from limited two-photon absorption cross sections and low photoluminescence efficiency. Herein, we systematically investigate the photophysical properties of experimentally reported molecules (2PhCzTPN, 2TPATPN, TPCzTPA, TPCz1NP, and TPCz2NP) in toluene based on first-principles calculations combined with the thermal vibration correlation function (TVCF) method. Furthermore, a novel near-infrared TPA-TADF molecule (TPCz2NP-2CN) is theoretically designed through an acceptor fusion strategy, providing insights into the underlying mechanisms of acceptor fusion-mediated regulation of two-photon absorption and delayed fluorescence. Our findings reveal the influence of acceptor modulation on the photophysical properties of TPA-TADF molecules and offer a rational molecular design strategy for the development of high-performance TPA-TADF materials featuring enhanced emission efficiency and two-photon absorption performance.