Green deep-eutectic synthesis of multinary quantum dots for luminescent polymeric composites and LED applications

Abstract

The production of a range of multinary quantum dots (QDs), including both ternary phase silver indium sulfide (AIS) and copper indium sulfide (CIS), and their quaternary alloys with zinc sulfide (ZAIS and ZCIS), using a L-menthol and lauric acid deep eutectic solvent (DES) was investigated. This novel synthetic approach relies on the hydrophobic nature of the L-menthol–lauric acid DES to combine the typical reaction environment of hot-injection processes, commonly used for the production of high-quality QDs, with the highly desirable qualities of deep eutectics as green solvents. The deposition of a zinc sulfide shell was also investigated, achieving an improvement of the photoluminescence quantum yield up to 65%. Moreover, the incorporation of multinary QDs produced in the L-menthol–lauric acid DES into polymethyl methacrylate (PMMA) matrices was investigated, yielding both bulk slabs and colour-converting layers for white and monochromatic LEDs. These studies clearly demonstrate the feasibility and advantages of DES-based synthesis for the production of high-quality multinary QDs and their incorporation into luminescent polymeric composites with strong potential for photonic and energy applications.