Electron‐Rich Cores Empower Organic C‐Shaped Dyes With Emission Peaking Around 1000 nm, 14.3% PLQY, and >3% EQE in OLEDs

Abstract

ABSTRACT We establish a molecular design blueprint for highly emissive, metal‐free organic NIR emitters by integrating an electron‐rich S,N‐heteroacene core into a C‐shaped architecture, affording CT‐F, and further extending this framework through selenium incorporation to generate the S,Se,N‐heteroacene‐based CT‐Se and CT‐2Se. This molecular architecture synergistically enhances intramolecular charge transfer (ICT) while suppressing internal reorganization energy through increased molecular rigidity. The optimized CT‐F dye achieves a solid‐state photoluminescence quantum yield of 14.3% at 970 nm. Incorporation of CT‐Se into a hyperfluorescent OLED employing a transfer‐printed sensitizer and balanced charge injection yields an external quantum efficiency (EQE) of 3.07% at 1000 nm, whereas introducing an additional PM6 buffer layer enables relay‐type interfacial energy transfer, elevating the EQE to 3.56% at 995 nm. Comprehensive mechanistic studies reveal that electron‐rich core–driven ICT modulation, molecular rigidification with controlled stacking, asymmetric vibronic coupling regulation, and balanced intrinsic charge transport cooperatively establish an omnidirectional optimization strategy for achieving high‐efficiency organic OLEDs peaking around 1000 nm and extending into the NIR‐II region.