Thermally active delayed fluorescence (TADF) materials show great potential as emitters in the organic light-emitting diodes (OLEDs), due to their capacity to harvest both singlet and triplet excitons and convert these into light. This is possible as a result of fast reverse intersystem crossing (RISC), which can occur in systems with small singlet-triplet energy gaps (DEST) and outcompetes non-radiative decay pathways. In traditional donor-acceptor TADF compounds, the small DEST results from the small exchange integral of the frontier orbitals that is possible in strongly twisted conformations where the donor and acceptor are mostly electronically decoupled. A consequence of this molecular design that leads to long-range charge transfer (LRCT) excited states is that the emission spectrum is broad, characterized by a full width at half maximum (FWHM) larger than 70 nm. Thus, OLEDs using D-A TADF emitters typically show poor color purity. Notably, to obtain the blue electroluminescence (EL) that can meet the BT.2020 standard, i.e., CIEy ≤ 0.05, without significant loss of efficiency caused by the use of color filters or microcavities will require the use of narrowband emitters. In 2016, Hatakeyama and co-workers reported the first examples of boron-based multiresonant TADF (MR-TADF) emitters, which showed simultaneously high photoluminescence quantum yields (FPL), sufficiently small DEST, and narrowband blue emission (FWHM of 28 nm). This seminal work has catalyzed significant efforts towards the development of boron-containing analogs, and also led to the expansion of the chemical space of MR-TADF emitters towards derivatives with the p-dopant replaced by carbonyl moieties. The oxygen-bridged boron-contained MR-TADF emitter DABOA (2a) was the first p-, and n-doped polycyclic aromatic hydrocarbon reported by Hatakeyama. This compound shows near-UV narrow emission, with a lPL of 398 nm and a FWHM of 34 nm in toluene solution. Since this first report in 2015, many derivatives of DABOA (aka DOBNA) have been reported, where DOBNA frequently takes the role of a weak acceptor in donor-acceptor TADF emitters. In 2019, both Liao's group and our group reported some of the first examples of ketone/nitrogen-based MR-TADF emitters (DiKTa, aka QAO), the OLEDs achieved an EQEmax of 14.7%, with lEL of 465 nm and FWHM of 39 nm. Numerous derivatives of DiKTa have since been reported, with the corresponding OLEDs achieving EQEmax in some examples of greater than 30%. Despite these impressive advances, devices that can produce the desired pure blue emission (CIEx + CIEy <0.3) remain rare.