Modulating LUMO extension of Spiro-junction TADF emitters for efficient OLEDs with relieved efficiency Roll-Off

Multi-spiro junctions enable efficient thermally activated delayed fluorescent emitter

“…Through rational decoration, the EQE of devices based on D–spiro–A compounds has been elevated to 20%. 18 In addition to their unique electronic features, the distinctive crisscross geometry of SAs imparts high rigidity to the emitters, which could on one hand effectively suppress the non-radiative decay for high photoluminescent quantum efficiency (PLQY), and on the other hand, improve the thermal stability. These advantages have been incorporated into recently emerged MR emitters for both high EQEs and excellent color purity.…”

Enhancing Reverse Intersystem Crossing in Triptycene-TADF Emitters: Theoretical Insights into Reorganization Energy and Heavy Atom Effects

“…7,8 Enhancing RISC processes is beneficial for reducing the efficiency roll-off and achieving superior performance in OLEDs. 2,9,10 Twisted molecular configurations effectively separate the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of TADF emitters, resulting in the reduction of the overlap integral and ΔE ST . However, this is unfavorable for the fluorescence emission processes from S 1 to the ground state (S 0 ).…”

Controllable construction of red thermally activated delayed fluorescence molecules based on a spiro-acridine donor

“…37,38 Yang’s group designed and synthesized a series of TADF emitters based on spiro-junction via a LUMO extension strategy to optimize the roll-off and comprehend the structure–property relationship. 39 Concurrently, they also developed two red-emitting TADF molecules by using the spiro type structure as the donor, and they found that the spiro type structure can help form a linear molecular structure and preferential horizontal emitting dipole orientation. 40 Moreover, Su and co-workers utilized a spiro TADF moiety as a functional electron donor in TADF molecular design toward efficient multichannel reverse intersystem crossing.…”