Constructing solution-processable heavy metal platinum (II) complex with narrowband emission by integrating multiple resonance molecular system

The narrowband emission required by wide color gamut display is an extremely important research topic for any luminescence mechanism, which has made significant progress in traditional fluorescence and thermally activated delayed fluorescence (TADF) based on purely organic compounds, but is far from mature in organometallic complexes. Herein, we propose a feasible molecular design paradigm for constructing the desirable organic electroluminescence (EL) emitter with narrowband emission by integrating an original multiple resonance TADF (MR-TADF) fragment into the classical platinum (II) complex. The solution-processed organic light-emitting diode (OLED) by employing the target model platinum (II) complex BNCPPt as the dopant emitter shows light green emission with a peak of 507 nm and narrow full-width at half-maximum (FWHM) of 35 nm, which achieves a maximum external quantum efficiency (EQE) of 13.5% with very low efficiency roll-off of 4.4% at 1000 cd m−2.