Multifunctional Dithiol Crosslinking Additive Enables Highly Efficient and Stable Inkjet‐Printed Perovskite Quantum Dot Light‐Emitting Diodes

Abstract Inkjet printing provides a scalable, cost‐effective approach for fabricating perovskite quantum dot light‐emitting diodes (Pe‐QLEDs), particularly suited for high‐resolution display applications. However, challenges such as poor ink printability and limited stability of perovskite quantum dots (Pe‐QD) inks have impeded its widespread adoption. To overcome these limitations, 1,4‐bis(3‐mercaptobutyryloxy)butane ( BD1 ), a dithiol‐based cross‐linkable additive is introduced to enable high‐performance inkjet‐printed Pe‐QLEDs. BD1 serves three critical functions: i) it optimizes the rheological properties of the ink, promoting uniform droplet formation and adaptable inkjet printing process; ii) its thiol groups coordinate with under‐coordinated Pb 2 ⁺ sites on the QD surface, mitigating ligand loss during ink formulation and deposition, thus reducing defect density and enhancing optical quality; and iii) it participates in a thiol‐ene click reaction with oleic acid ligands, forming robust crosslinked networks that improve film integrity and device stability. By leveraging these synergistic effects, BD1 ‐enabled Pe‐QLEDs achieve a record‐high external quantum efficiency (EQE) of 21.73%, a peak luminance of 30,637.82 cd m − 2 , and an enhanced operational lifetime. This additive engineering strategy also demonstrates versatility across red and blue Pe‐QLEDs, highlighting its broad applicability. Collectively, the findings position BD1 as a highly effective multifunctional additive for stabilizing and optimizing Pe‐QD inks, paving the way for scalable production of high‐resolution, full‐color Pe‐QLED displays and other printed optoelectronic devices.