We synthesized and characterized novel butterfly-like dinuclear Pt(II) complexes, Di-Pt-CH3 and Di-Pt-CD3, using non-fluorinated NHC ligands to reduce excited state bond cleavage. These complexes show phosphorescent emission in the 440-460 nm range in the film state, with shorter lifetimes due to a Pt-Pt distance of 3.21 Å. Efficient energy transfer to the singlet state of blue MR-TADF emitters, t-DABNA and n-DABNA, was achieved from the 3IL and 3MLCT mixed states of the Pt(II) complexes. The TADF emitter's delayed triplet lifetime was shortened by fast relaxation of the 3MMLCT states, which have 0.07 eV lower energy than the TADF emitters' triplet states. Di-Pt-CH3 and Di-Pt-CD3 were used in phosphorescent and PS-TADF blue OLEDs, achieving high EQEs of 18.3% and 25.4%, respectively, with the PS-TADF OLED displaying a low roll-off of 3.2%. The deuterium-substituted methyl group (-CD3) significantly improved the device lifetime in both PhOLEDs and PS-TADF OLEDs.