Air stable eco-friendly quantum dots with a light-mediated photoinitiator for an inkjet printed flexible light emitting diode. Issue 29 (14th July 2022)

• Record Type: Journal Article
• Authors: Lee, Hanleem; Suh, Yo-Han; Fan, Xiang-Bing; Ni, Limeng; Yang, Jiajie; Kim, Yoonwoo; Jo, Jeong-Wan; Choi, Hyung Woo; Jung, Sung-Min; Shin, Dong-Wook; Lee, Sanghyo; Kim, Jong Min
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 29(2022)
• Page Start: 10708
• Page End: 10718
• Publication Date: 2022-07-14
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc00851c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Large-scale printed InP RGB quantum dot (QD) light emitting diodes (QLEDs) are realised by an air-processable and stable ink with a photoinitiator (PI) mediating cross-linkage between eco-friendly QDs for next generation self-emissive display. Abstract : Printed quantum dot (QD) light emitting diodes (QLEDs) over a large scale have received much interest in the last decade owing to the demand for the next generation of self-emissive large-area displays. To realize printing technology for QLEDs, a pioneering study suggested using a co-solvent system or a polymer additive in CdSe-based QLEDs. However, limitations on printed QLEDs with eco-friendly QDs, including the selection of ink solvent, environmental degradation of QDs in the air by temperature and O2 /H2 O level, and viscosity, make it difficult to achieve higher luminescence and external quantum efficiency (EQE) than that of ionic-bonded Cd-based QDs. Herein, we design an air-processable and stable ink with a photoinitiator (PI) mediating cross-linkage between eco-friendly QDs for inkjet-printed QLEDs. Once QD inks with a PI are deposited on the desired surface, their film polymerizes in situ through radical formation induced by ultraviolet (UV) exposure. Cross-linking reactions between ligands in the QDs reduce the distances between them, leading to flattening of the surface and enhancement of environmental stability in air. Printed InP-based green QLEDs demonstrated maximum luminescence values of 3600 cd m −2 at 10 V on ITO/glass for the very first time. Finally, large-scale InP red/green/blue QLEDs directly printed with a bird image were fabricated on the flexible substrate.