Multiresonant thermally activated delayed fluorescence (MR-TADF) compounds hold great potential as emitters in organic light-emitting diodes (OLEDs) as devices with these materials can achieve simultaneously high efficiencies and saturated colors. Distinct from traditional donor-acceptor (D-A) TADF emitters, MR-TADF emitters typically are p-and n-doped nanographenes. Their rigid molecular structures suppress vibronic modes and result in small geometric reorganization in the excited states, resulting in narrow full width at half maxima (FWHMs, typically <50 nm) and small Stokes shifts of less than 30 nm. The origin of the TADF in MR-TADF emitters results from their distinct frontier molecular orbital (FMO) distributions, leading to an alternating pattern of increasing and decreasing electron density in the excited states compared to the ground state that is responsible for the suitably small singlet-triplet energy gap, DEST. This distribution pattern leads to these materials emitting from a short-range charge-transfer (SRCT) excited state. Moreover, as the electron density globally resides across the same atoms, the oscillator strength for the SRCT transitions is high, resulting in fast radiative decay rate constants (kr), manifested in high photoluminescence quantum yields (FPL). However, in most MR-TADF systems, the RISC rate constants (kRISC) typically struggle to reach even 10 4 s -1 , which are much slower than those of most advanced D-A TADF emitters. Such slow kRISC values are disadvantageous for efficient triplet harvesting, and the accumulation of long-lived triplet excitons, especially at high current densities, are responsible for deleterious triplet exciton-related annihilation processes, such as triplet-polaron annihilation (TPA) and triplet-triplet annihilation (TTA), that give rise to lower efficiencies and severe efficiency roll-off in the device. Recently, there have been a few reports of MR-TADF emitters that have fast kRISC of over 10 5 s -1 , and their use in devices translated into OLEDs exhibiting high efficiency and mild efficiency roll-off. However, these emitters typically suffer from aggregation-caused quenching even at low concentrations, and emission broadening, both of which unduly affect the device performance. A more widely used solution to tackle the drop in performance in the device due to the use of an MR-TADF emitter with too slow kRISC is the addition of a fast kRISC D-A TADF material within the emissive layer (EML) that acts as a sensitizer, i.e., so-called hyperfluorescent OLEDs (HF-OLEDs). In these devices, triplet excitons are first formed on the assistant dopant that then rapidly convert to singlets before being transferred to the MR-TADF terminal emitter via Förster resonance energy transfer (FRET), thus leading to more efficient triplet harvesting in the device. Taking a benchmark MR-TADF emitter DtCzBN (also known as BCz-BN) as an example (Figure ), when the OLED was fabricated containing a conventional binary EML with 1 wt% DtCzBN in 3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) host, although a high maximum external quantum efficiency (EQEmax) of 21.6% was achieved, the efficiency dropped precipitously to 5.3% at a luminance of 1000 cd m -2 . 32 By contrast, the device possessing a ternary emissive layer containing 20 wt% of the TADF sensitizer CTPCF3 not only showed a higher EQEmax of 27.5%, but more importantly, the efficiency roll-off was much reduced, with the EQE1000 maintained at 24.1%. However, as the kinetics of FRET are largely dependent on the spectral overlap and the distance between the energy donor (the sensitizer) and acceptor (the terminal emitter), precise control of their concentration within the ternary EML is needed for optimal device performance. Here, we propose a molecular design where the functionalities of the assistant dopant and terminal emitter are embedded within a single molecule, thus ensuring efficient FRET between the two.