Overcoming QLED efficiency limitations by quantum dot film thickness optimization
A collaborative team of researchers from Lehigh University and the University of Washington have achieved new significant advancements in Quantum Dot Light-Emitting Diodes (QLEDs) by optimizing the blade-coating method for Quantum Dot (QD) film deposition. The team detail how control over the thickness and uniformity of QD films can be used to optimize QLEDs, reporting their findings in the journal ACS Nano.
QLED blade-coating approach
Blade-coating is a scalable and low-waste solution suitable for large-area deposition of QD films. In this case this aspect of the work is restricted to the Landau-Levich regime, where the thickness of the liquid film deposited scales with the coating speed. Operating under this regime permits higher coating rates and is compatible with rapid film printing relevant to scale-up.
Optimizing QD film thickness
The mechanics pursued an organized search of blade speed influence in QD film morphology and thickness. It achieved the best coverage of a QD film (−163% surface coverage) and low roughness to boost the performance of QLEDs.
Impact on QLED efficiency
Using commercially available CdSe/ZnS QDs, QLEDs with an external quantum efficiency (EQE) of ∼1.5% were obtained from the optimized blade-coating process. Using native InP/ZnSe/ZnS QDs with increased PLQY, the researchers reached an EQE of about 7%.
Conclusion
This work reveals the promise of blade-coating as a scalable, low-cost, high-throughput solution for QLED manufacture. The team facilitated improved QLED performance through controlled film thickness and morphology control of QDs which can benefit the path of future development of display technologies. Reference Landau–Levich Scaling for Optimization of Quantum Dot Layer Morphology and Thickness in Quantum-Dot Light-Emitting Diodes
Yiman Xu, Grant J. Dixon, Qing Xie, James F. Gilchrist, Brandi M. Cossairt, David S. Ginger, Elsa Reichmanis https://pubs.acs.org/doi/10.1021/acsnano.4c15912 Nanotechnology World (NW)
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