“Rate-limited effect” of reverse intersystem crossing process: the key for tuning thermally activated delayed fluorescence lifetime and efficiency roll-off of organic light emitting diodes

Abstract

The rate constant of reverse intersystem crossing was found to be the “rate-limited step” in thermally activated delayed fluorescence lifetime governing.

3.2: Singlet‐Triplet Splitting Energy Management via Acceptor Substitution: Complanation Molecular Design for Deep‐Blue Thermally Activated Delayed Fluorescent Organic Light‐Emitting Diodes

“…The reason can be ascribed to the long τTADF from small kRISC as RISC process plays "ratelimited effect" role in controlling excited state lifetime of delayed fluorescence. (26) The large ΔEST of TADF emitters invalidate the up-conversion process from T1 to S1, increasing the triplet exciton density as high triplet exciton generation ratio (three-fourths) under electric operation. As a result, processes like singlet-triplet annihilation (STA), triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA) can take place and lead to severe efficiency roll-off at high current density.…”

Manipulating the Stacking of Triplet Chromophores in the Crystal Form for Ultralong Organic Phosphorescence

“…Thei nitial decrease of the total emission intensity was attributed to the competing process between phosphorescence (see Figure S15) and TADF emission upon an increase in temperature. [15] In the amorphous films,h owever,c haracteristic phosphorescence emissions in the crystal disappeared when dispersed in the PMMA matrix (see Figures S16 and S17 and Table S3). In amore rigidified Zeonex matrix, bluegreen phosphorescence can only be detected in a2 4CPhCz/ Zeonex film with the main peak at 495 nm and al ifetime of 30.55 ms under an N 2 atmosphere (see Figure S18).…”

Synthesis of pyrazine‐2,3‐dicarbonitriles via the one‐pot three‐component reaction of 4‐benzoyl‐5‐phenylamino‐2,3‐dihydrothiophene‐2,3‐dione, diaminomaleonitrile, and functionalized alcohols in acetonitrile

“…[20] 2,3-Dicyanopyrazines are very powerful electron acceptors and are especially suitable building blocks for the functional dyes and nonlinear optical materials (NLOs). [24][25][26][27][28] Pyrazine-2,3-dicarbonitriles may be used as precursors for tetrapyrazinoporphyrazines (TPyzPzs), the heterocyclic aza analogs of the phthalocyanines (AzaPcs). [24][25][26][27][28] Pyrazine-2,3-dicarbonitriles may be used as precursors for tetrapyrazinoporphyrazines (TPyzPzs), the heterocyclic aza analogs of the phthalocyanines (AzaPcs).…”