Meniscus‐Guided Molecular Alignment for High‐Efficiency Solution‐Processed DR/NIR‐OLEDs

Abstract Low‐cost, solution‐processed organic light‐emitting diodes (OLEDs) have garnered significant attention for large‐area and flexible wearable applications. However, the solution‐based fabrication process often results in disordered molecular packing and random dipole orientation, leading to inferior electroluminescence efficiency compared to vacuum‐deposited devices. Here, a high‐efficiency deep‐red/near‐infrared OLED is demonstrated achieved through meniscus‐guided coating technology, which enables precise control over emitter alignment in the emissive layer. This off‐center spin‐coating technique promotes tighter π–π stacking and lamellar packing along the radial shear direction, yielding a dramatically enhanced horizontal dipole ratio (73% vs 54% in conventional on‐center spin‐coated films), a 2.5‐fold increase in photoluminescence quantum yield, and improved charge transport balance. As a result, the optimized device achieves a record external quantum efficiency (EQE) of 17.6% in the 600–800 nm range—a 2.4‐fold enhancement over the on‐center spin‐coated counterpart with an EQE of 7.4%. This approach provides a generalizable strategy for controlling molecular orientation in solution‐processed optoelectronics without additional post‐treatment steps.