RTP is the radiative transition from molecular triplet excitons at room temperature, together with a phosphorescence lifetime, tPh, that is typically on the order of microseconds or even longer. OLEDs with RTP emitters are able to harvest 100% of the excitons to produce light. The majority of reported RTP luminophores are organometallic complexes, where the metals, such as platinum (Pt) and iridium (Ir), can effectively enhance spin-orbit coupling and thus boost both intersystem crossing (ISC) and radiative emission rates from the triplet manifold. Nevertheless, it remains a significant challenge to develop high-performance purely organic RTP emitters, as in these compounds that have a large S1-T1 energy gap (DEST) there is weak spin-orbit coupling between singlet and triplet states. To date, the most popular organic RTP design paradigms mainly follow two strategies: 1) boosting ISC by, for instance, introducing carbonyl groups and/or halogens into a molecule; 2) suppressing triplet nonradiative processes through, for instance, crystallization, supramolecular assembly, or matrix rigidification. Notably, most RTP emitters generally obey Kasha's rule, where phosphorescence originates from T1, and the observation of multiple phosphorescence in a single molecule, a violation of Kasha's rule, has rarely been documented. The observation of multiple phosphorescence provides insight into high-lying triplet excited-state dynamics, as we recently documented for a naphthalene-based system. The present study focuses on the design of molecular donor-acceptor composites based on tetradonor-substituted corannulenes with phenylene bridges to TCzPhCor, TDMACPhCor, and TPXZPhCor (Figure ). We demonstrated utility of these RTP materials in an afterglow OLED and for optical temperature sensing stemming from a change in the ratio of multiple phosphorescence yields as a function of temperatures. These results demonstrate the promise of corannulene materials to define a new structure space for optoelectronic materials useful for modern device technology and engineering.