 The study presents two new iridium complexes with bulky TMS groups that are doped with a terminal emitter to create efficient triplet harvesting through cascade-resonant energy transfer. The resulting hyper-OLEDs have a high external quantum efficiency of 31.06 percent, pure blue emission peak at 467 nanometers, and a converted lifetime of up to 4,552 hours at 100 candelas M carat-2. These findings demonstrate the effective use of bulky TMS substituent 3 plus 2 plus 1, iridium, 3 complexes as sensitizers for high efficiency and stable blue OLEDs in display and lighting applications. This article was authored by Qingqing Wu, Kining Tung, Kefi Shure, and others.