Periodically corrugated organic light-emitting diodes (OLEDs) based on triangular lattice structures represent a significant advancement in enhancing light outcoupling efficiency. By conformally growing all device layers—including the emissive region, electron transport layer (ETL), hole transport layer (HTL), and transparent electrode—on a nanostructured photonic substrate, these devices exploit diffraction effects to redirect trapped waveguided and surface plasmon modes into the air emission cone. This work presents a comprehensive computational analysis using a rigorous scattering matrix framework that accounts for vectorial Maxwell’s equations across all polarization states.
The study focuses on a polycarbonate (PC) substrate with a refractive index of 1.58, which improves index matching with high-index organic materials compared to conventional glass. The periodic corrugations are modeled as slanted cones with flat tops, maintaining triangular lattice symmetry and consistent pitch (a) and height (h) throughout the stack. Numerical simulations are performed for three representative wavelengths: red (610 nm), green (530 nm), and blue (470 nm). The dipole emission is assumed isotropic, with emitters distributed along ring-like contours around each nanocone, reflecting realistic conformal growth observed experimentally.
Key findings reveal that optimal outcoupling efficiencies of 60–65% are achieved when the corrugation pitch lies within the range of 1000–2500 nm. At this scale, first-order diffraction via reciprocal lattice vectors G₁ and G₂ effectively couples guided modes from both the organic layer and substrate back into the air cone. This mechanism enables efficient redirection of photons that would otherwise be lost due to total internal reflection or plasmonic absorption. Notably, the outcoupling efficiency remains robust even when corrugation heights exceed 100 nm, indicating minimal sensitivity to fabrication variations in vertical dimension—an important advantage for real-world implementation.
For smaller pitches (a < 500 nm), outcoupling drops sharply due to insufficient momentum transfer by higher-order diffraction processes, while large pitches (a > 3000 nm) result in gradual roll-off as the structure approaches the flat limit. In both extremes, waveguiding losses dominate, reducing overall performance. However, at optimal pitches, waveguided losses are reduced to approximately 30%, and plasmonic losses remain below 10%, confirming the effectiveness of the corrugation design in suppressing non-radiative pathways.
The angular emission profile shows weak anisotropy depending on the direction of the parallel wave vector k|| relative to the lattice axes. Emission along the y-axis exhibits slightly better coupling than along x due to favorable alignment with G₂, but averaging over multiple directions yields nearly isotropic output. This behavior is confirmed by k-space projections showing how diffraction vectors match the boundaries of the emission cone only within the optimal pitch window.
Additionally, parametric studies reveal that the base width (R) of the nanocones significantly influences performance. Cones with R > 0.2a yield superior outcoupling, while excessively narrow bases lead to increased waveguiding. The top-to-base ratio (Rₜ/R = 0.2) is kept constant, ensuring structural consistency. Varying the cone apex angle has minor impact on efficiency near optimal pitch, though narrower tops slightly reduce outcoupling by ~5% due to altered mode confinement.PGRMC1 Antibody Epigenetics
These results validate the potential of triangular lattice corrugations as a scalable platform for ultra-efficient OLEDs.DBT Antibody supplier Experimental validation from prior work—such as EQE values of ~50% measured in devices with pitch ~750–800 nm—align closely with our predicted outcoupling levels, supporting the model’s accuracy.PMID:35083152 Future integration of external microlens arrays or dual-periodic structures could further enhance performance, particularly for white OLED applications requiring balanced spectral output.
In conclusion, triangular lattice corrugated OLEDs offer a powerful solution to the long-standing challenge of low light extraction. With demonstrated efficiencies exceeding 60% and strong tolerance to process variations, they represent a transformative step toward high-brightness, energy-efficient solid-state lighting and next-generation displays.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
