Reverse intersystem crossing (RISC), is a photophysical process that converts triplet excitons to singlet excitons. RISC is central to the thermally activated delayed fluorescence (TADF) mechanism where the process is endothermic and converts non-emissive triplet excitons to emissive singlet excitons. Organic light-emitting diodes (OLEDs) with compounds that emit TADF can achieve 100% internal quantum efficiency (IQE). For TADF to be operational, the energy gap between the lowest-lying singlet (S1) and triplet (T1) excited states, DEST, must be sufficiently small, normally taken to be less than 200 meV. The most common design rule for TADF emitters includes poorly electronically coupled electron donor (D) and acceptor (A) moieties in order to confine the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) on the donor and acceptor units, respectively. The resulting small exchange integral induces a small ΔEST. Using this molecular design requires very electronically weak donor and acceptor groups in order to achieve high-energy emissive S1 states for blue TADF emitters.