Enhanced Performance of Inkjet Printed Red Quantum Dot Light-Emitting Diodes Influenced by ETL Uniformity with Solvent Systems

Abstract

Inkjet printing of electroluminescent quantum dots (EL-QDs) is a promising approach for fabricating the next generation of full-color display panels. However, commercialization and practical application are hindered by the low efficiency and short operational lifetime of the EL-QDs, primarily attributed to solvent-related issues for the inkjet printing process. Here, a mixed-solvent system with a high boiling point is presented to enhance the EL-QD performance by improving film uniformity and suppressing the coffee-ring effect. Combining solvents D1 with T1 increases the viscosity and boiling point, allowing precise evaporation control and reducing drying inconsistencies across large-area substrates. This system facilitates better droplet spreading and pattern fidelity, resulting in enhanced pixel uniformity. In experiments, EL-QDs fabricated with the mixed-solvent system exhibited significantly enhanced device performance compared to those fabricated with a single-solvent system. CdSe-based EL-QDs achieved a 403.8% increase in luminance and a 313.2% improvement in operational lifetime, demonstrating improved stability and brightness. Furthermore, InP-based EL-QDs exhibited a 453.8% increase in luminance and a 238.4% improvement in external quantum efficiency (EQE), validating the mixed-solvent approach in improving efficiency. These findings emphasize the benefits of mixed-solvent systems in achieving high-quality EL-QD deposition via inkjet printing, offering a promising strategy for next-generation display applications.