Capping Ligand Engineering of Cadmium‐Free AIZS Quantum Dots Toward Bright Electroluminescent Light‐Emitting Diodes by All‐Solution Process

Abstract

AbstractCadmium‐free AgInZnS (AIZS) quantum dots (QDs) have garnered significant research interest for applications in light‐emitting diodes (LEDs); however, their performance remains limited by insulating long‐chain ligands. In this study, highly fluorescent orange‐emitting AIZS QDs are synthesized by replacing long‐chain 1‐dodecanethiol (DDT) with short‐chain 1‐octanethiol (OTT), achieving photoluminescence quantum yields of up to 80% in solution and 60% in film. The incorporation of OTT in combination with oleic acid and oleylamine as co‐capping ligands enabled excellent dispersion of the QDs in non‐polar solvents. The resulting OTT‐capped AIZS QDs exhibited improved film smoothness and reduced nonradiative recombination. Furthermore, all‐solution‐processed QD light‐emitting diodes (QLEDs) are fabricated comprising indium tin oxide/poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate/hole transporting layer/AIZS QDs/ZnO electron transporting layer/Al. The effects of OTT capping and the thickness of the AIZS emitting layer on device performance are systematically evaluated. As a result, the QLEDs demonstrated enhanced luminance and current efficiency, reaching 515 cd m−2 and 0.4 cd A−1 respectively, representing improvements of over 50% and 33% compared to devices utilizing DDT‐capped AIZS QDs. This study presents a facile and effective approach for developing high‐brightness AIZS QLEDs.