Overlapping Nanostacks Enable Direct Printing of Organic LEDs

A custom-built laser-induced forward transfer (LIFT) setup was developed to fabricate multimaterial organic light emitting diode (OLED) stacks under ambient laboratory conditions without the use of a cleanroom or encapsulation. The process enables precise control of layer thickness through parameter tuning as confirmed by vertical scanning interferometry (VSI), yielding smooth and homogeneous layers with surface roughness values down to 2.78 nm. The process achieves tunable thicknesses between 19 nm and 45 nm, while the lateral resolution is limited to about 100 μm. A three-layer OLED stack (total thickness ≈ 90 nm) was printed and structurally characterized using focused ion beam scanning electron microscopy (FIB-SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), revealing distinct, well-defined layer boundaries. First functional tests demonstrated electroluminescence at 580 nm with an operational lifetime of at least 20 min. Despite the lack of encapsulation, the OLEDs remained stable under ambient conditions with a shelf life of up to 9 days. These results confirm the potential of LIFT as a scalable and precise tool for the additive manufacturing of flexible thin-film devices such as OLEDs, solar cells and fuel cells.