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

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2019, Vol.7 (15), p.459-4516
• Main Authors: Sicilia, Violeta, Fuertes, Sara, Chueca, Andrés J, Arnal, Lorenzo, Martín, Antonio, Perálvarez, Mariano, Botta, Chiara, Giovanella, Umberto
• Format: Article
• Language: English
• Subjects: Chelates; Crystallography; Density functional theory; Diodes; Emission analysis; Emitters; Organic light emitting diodes; Phosphors; Photoluminescence; Platinum; Polymethyl methacrylate; Solid state; Thermal stability; Time dependence; White light
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c9tc00747d

New cycloplatinated N-heterocyclic carbene (NHC) compounds with chelate diphosphines (P^P) as ancillary ligands, [Pt(R-C^C*)(P^P)]PF 6 (R-C = Naph, P^P = dppm 1A , dppe 2A , dppbz 3A ; R = CO 2 Et, 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 (CO 2 Et-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 uv values and a great range of nominal CCT (4000-2000 K) was obtained. The new compounds [Pt(R-C^C*)(P^P)]PF 6 as blue or orange emitters were combined with the red emitter [Pt(bzq)(CN)(CNXyl)] to fabricate two-component WOLEDs and pcWLEDs. They rendered warm white light with optimal CRI and D uv values and a great range of nominal CCT: 4000 K-2000 K.