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

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.