 Abstract purely organic room temperature phosphorescence, RTP, materials typically have low quantum yields and long lifetimes due to theoretical spin forbidden triplet states. In this study, a new class of RTP materials was created using a donor acceptor, DA, skeleton with a phenoxycellanine donor. The DA's skeleton allowed for increased orbital angular momentum change, resulting in higher spin orbit coupling and reduced non-radiative energy loss. This combination of factors resulted in a record high external quantum efficiency of 19.5%, making these materials ideal candidates for use in organic light emitting diodes, OLEDs. Additionally, voltage-dependent color tunability and single molecule white emission were demonstrated. This article was authored by Zijin Chen, Minkli, Chingu, and others.