Improving the Blue Color Purity of Tetradentate Pt(II) Complexes with the Assistance of F⋅⋅⋅H Interaction towards High-Performance Blue Phosphorescent OLEDs with EQE over 33 .

Among the various challenges in the field of organic light-emitting diodes (OLEDs), simultaneously achieving high efficiency, a long lifespan, and a narrow full-width at half maximum (FWHM) in blue OLEDs remains a significant hurdle. Herein, we demonstrate a strategy to improve the color purity of tetradentate Pt(II) complexes with the assistance of ⋅⋅⋅H interaction by incorporating trifluoromethyl (-CF3) groups into the well-known blue tetradentate Pt(II) phosphorescent complex. The results show that the different substitution positions of -CF3 have significantly varying effects on the FWHM values of the complexes; specifically, introducing -CF3 on the benzene ring of carbazole effectively reduces the FWHM, while introducing it on the benzene ring linked to the carbene unit has a minimal impact. When utilized in a mixed host system of SiCzCz/SiTrzCz2, the OLEDs with these new complexes as emitters demonstrated maximum external quantum efficiencies (EQEs) of 27.1 %, 33.8 %, and 27.6 % for PtON-CF3-1, PtON-CF3-2, and PtON-2CF3, respectively, with excellent color purity (CIEy≈0.14 for the PtON-CF3-2 based device). Notably, the device based on PtON-CF3-2 matched the stability of the benchmark PtON-TBBI complex.This work offers an important guideline for the design of high efficient Pt(II) phosphorescent complexes with good blue color purity.