Improved color quality in double-EML WOLEDs by using a tetradentate Pt(ii) complex as a green/red emitter

A simple device structure adopting double emitting layers (EMLs) for white organic light-emitting diodes (WOLEDs) is described. The white emission is composed of blue emission from an Ir(III) complex in the blue EML and green/red emission from a single tetradentate Pt(II) complex Pt–X-4 in the green/red EML. High color rendering index (CRI) of 81 and high external quantum efficiencies of up to 19.85% are achieved for this WOLED. In addition to the broad emission spectrum and high efficiency, the short emission lifetime of Pt–X-4 in the aggregate form enables a high luminance of nearly 1 00 000 cd m−2 and low efficiency roll-offs of 2.1% and 11% at 1000 and 10 000 cd m−2, respectively. The simple device structure with high efficiency at high luminance and decent CRI value renders this WOLED a potential candidate for next-generation illumination devices.