A Universal Ternary‐Solvent‐Ink Strategy toward Efficient Inkjet‐Printed Perovskite Quantum Dot Light‐Emitting Diodes

Abstract Toward next‐generation electroluminescent quantum dot (QD) displays, inkjet printing technique has been convinced as one of the most promising low‐cost and large‐scale manufacturing of patterned quantum dot light‐emitting diodes (QLEDs). The development of high‐quality and stable QD inks is a key step to push this technology toward practical applications. Herein, a universal ternary‐solvent‐ink strategy is proposed for the cesium lead halides (CsPbX 3 ) perovskite QDs and their corresponding inkjet‐printed QLEDs. With this tailor‐made ternary halogen‐free solvent (naphthene, n ‐tridecane, and n ‐nonane) recipe, a highly dispersive and stable CsPbX 3 QD ink is obtained, which exhibits much better printability and film‐forming ability than that of the binary solvent (naphthene and n ‐tridecane) system, leading to a much better qualitied perovskite QD thin film. Consequently, a record peak external quantum efficiency (EQE) of 8.54% and maximum luminance of 43 883.39 cd m −2 is achieved in inkjet‐printed green perovskite QLEDs, which is much higher than that of the binary‐solvent‐system‐based devices (EQE = 2.26%). Moreover, the ternary‐solvent‐system exhibits a universal applicability in the inkjet‐printed red and blue perovskite QLEDs as well as cadmium (Cd)‐based QLEDs. This work demonstrates a new strategy for tailor‐making a general ternary‐solvent‐QD‐ink system for efficient inkjet‐printed QLEDs as well as the other solution‐processed electronic devices in the future.