Highly efficient platinum-based emitters for warm white light emitting diodes

New cycloplatinated N-heterocyclic carbene (NHC) compounds with chelate diphosphines (P^P) as ancillary ligands, [Pt(R-C^C∗)(P^P)]PF (R-C = Naph, P^P = dppm 1A, dppe 2A, dppbz 3A; R = COEt, P^P = dppm 1B, dppe 2B, dppbz 3B), have been prepared. Their photophysical properties have been extensively studied and supported by the time-dependent-density functional theory (TD-DFT). These compounds show a great thermal stability and a very efficient blue (COEt-C^C∗) or cyan (Naph^C∗) emission in PMMA films (5 wt%), with photoluminescence quantum yield (PLQY) ranging from 53% to 95%. In the solid state, the emission of the Naph^C∗ derivatives becomes orange (1A, 2A) or white (3A, dual blue and yellow emission) due to the operating π-π intermolecular interactions. We have investigated the potential use of these materials for solid-state lighting (SSL) applications. OLEDs with different architectures containing mixtures of 1B and 3A in different ratios as dopants were fabricated. In addition, two-component white light remote phosphors were obtained by stacking different combinations of 1B or 3B as the blue emitter with [Pt(bzq)(CN)(CNXyl)] (R) (bzq = benzoquinolate, Xyl = 2,6-dimethylphenyl) as the red emitter using a 365 nm LED as pumping source. By changing the blue:red ratio, warm white light with optimal CRI and D values and a great range of nominal CCT (4000-2000 K) was obtained.This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO)/FEDER (Project CTQ2015-67461-P led by Dr Babil Menjón) and by the Gobierno de Aragón and Fondo Social Europeo (Grupo E17_17R: Química Inorgánica y de los Compuestos Organometálicos led by Dr José M. Casas). The authors thank the Instituto de Biocomputación y Física de Sistemas Complejos (BIFI) and Centro de Supercomputación de Galicia (CESGA) for generous allocation of computational resources. U. G. and C. B. acknowledge the support of Project I-Zeb, III Accordo Quadro CNR-Regione Lombardia. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)