Efficient "Pure" blue OLEDs employing tetradentate Pt complexes with a narrow spectral bandwidth

A series of efficient 'pure' blue emitters with Commission Internationale de L'Eclairage (CIEy) values less than 0.1 were developed utilizing rigid tetradentate platinum (Pt) complexes. These emitters demonstrated dramatically reduced vibronic sidebands compared with their Pt and Ir analogs resulting in FWHM values of ca. 20 nm for peak emission between 440-450 nm. All the materials used in the devices were purified via train sublimation in a four-zone thermal-gradient furnace under high vacuum. Prior to deposition, the pre patterned ITO-coated glass substrates were cleaned by subsequent sonication in deionized water, acetone, and isopropyl alcohol. The relationship between the efficiencies in a device setting and the small triplet energy differences between the narrow band emitters suggests that the emission energy of these complexes may be near the limit for being compatible with common carbazole based host materials which tend to be aligned with stable materials for OLEDs with long operational lifetimes. Devices of PtON7-dtb, in particular, demonstrated external quantum efficiencies (EQEs) of 22.7% at 100 cd m^-2 peaking at 24.8% and CIE values of (0.148, 0.079) in a cohost structure.