Efficient Near‐Infrared Electroluminescence at 840 nm with “Metal‐Free” Small‐Molecule:Polymer Blends

• DOI: 10.1002/adma.201706584
• Publication Date: 2018-07-10T08:38:42Z
• Authors: Alessandro Minotto; Petri Murto; Zewdneh Genene; Andrea Zampetti; Giuseppe Carnicella; Wendimagegn Mammo; Mats R. Andersson; Ergang Wang; Franco Cacialli
• Keywords: organic light-emitting diodes (OLEDs); 02 engineering and technology; near infra-red; Polymer Chemistry; Condensed Matter Physics; near-infrared; 7. Clean energy; Blends; indacenodithiophene; Blends; Indacenodithiophene; Near-infrared; Organic light-emitting diodes (OLEDs); Triazolobenzothiadiazole; triazolobenzothiadiazole; blends; Other Chemistry Topics; 0210 nano-technology

Abstract Due to the so‐called energy‐gap law and aggregation quenching, efficiency of organic light‐emitting diodes (OLEDs) emitting above 800 nm is significantly lower than that visible ones. Successful exploitation triplet emission in phosphorescent materials containing heavy metals has been reported, with OLEDs achieving remarkable external quantum efficiencies (EQEs) up 3.8% (peak wavelength > nm). For incorporating fluorescent free from or toxic metals, however, we are not aware any report EQEs over 1% (again for peaking at wavelengths nm), even devices leveraging thermally activated delayed fluorescence (TADF). Here, development polymer (PLEDs) 840 exhibiting unprecedented (in excess 1.15%) turn‐on voltages as low 1.7 V reported. These incorporate a novel triazolobenzothiadiazole‐based emitter indacenodithiophene‐based transport matrix, affording excellent spectral properties. To best knowledge, such values ever reported electroluminescence purely solution‐processed active layer, triplet‐assisted emission.