A white OLED with a maximum EQE of 20.1%, CIE coordinates of (0.33, 0.33) and CRI of 80 is fabricated based on platinum(II) bis(N-methyl-imidazolyl)benzene chloride (Pt-16). The device emission spectrum and the chemical structure of Pt-16 are shown in the inset of the efficiency versus luminance graph.

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a b s t r a c tA highly efficient green microcavity organic light emitting diode was developed using a tetradentate cyclometalated platinum complex, PtN1N, with an intrinsically narrow emission spectral band (FWHM ¼ 18 nm). Devices employing the narrow band emitter in MOLEDs consisting of a single pair of a high index dielectric, Ta 2 O 5 , and low index dielectric, SiO 2 , exhibited a high peak external quantum efficiency of 33.7% compared to a standard OLED in the same device architecture with a peak external quantum efficiency of 25.6%. We have also found in our study that narrow band emission sources in tuned microcavity OLEDs exhibit larger enhancements in light out-coupling efficiency accompanied by small changes in color with respect to viewing angle compared to broad band emitters which is advantageous in display applications.

Highly efficiency stable, blue phosphorescent OLEDS are still in need of further development if OLEDs are to compete with existing lighting and display technologies. Here we present a possible route toward stable, blue phosphorescent OLEDs using halogen‐free platinum complexes. Devices based on the halogen‐free platinum complexes yielded external quantum efficiencies more than 20%.