Strategy for tuning the up-conversion intersystem crossing rates in a series of organic light-emitting diodes emitters relevant for thermally activated delayed fluorescence.

摘要: Abstract Accurate prediction on the up-conversion intersystem crossing rate (kUISC) is a critical issue for molecular design of an efficient thermally activated delayed fluorescence (TADF) emitter, and kUISC considered to be mainly determined by spin-orbit coupling matrix element (SOCME) singlet-triplet energy difference (∆EST). In present contribution, we strategically designed series organic molecules, bearing isoindole-dione core as electron acceptor (A) unit dinitrocarbazolyl, carbazolyl, diphenylcarbazolyl, dicarbazolyl tercarbazolyl groups donor (D) units, respectively. Their SOCME ∆EST values between S1 T1 states were calculated DFT TD-DFT methodes, rates estimated using semiclassical Marcus theory. The studies indicate that π-conjugation in D enhances, value gradually decreases, increases. molecule moiety found exhibit largest computations, high 1.22 × 106 s−1, which same order magnitude experimentally observed highly-efficient TADF emitter 4-benzoylpyridine A group moiety. results sufficiently prove necessity introducing strong electron-rich substituent when designing highly emitters.