Surface ligand chemistry on quaternary Ag(In<sub><i>x</i></sub>Ga<sub>1−<i>x</i></sub>)S<sub>2</sub> semiconductor quantum dots for improving photoluminescence properties
Watcharaporn Hoisang, Taro Uematsu, Tsukasa Torimoto, Susumu Kuwabata
Abstract
surface ligand engineering. Firstly, the use of a mixture of oleic acid and oleylamine, instead of only oleylamine, as the solvent for the QD synthesis was attempted, and a threefold improvement of the PL quantum yield was achieved. Subsequently, a post-synthetic ligand exchange was performed. Although the addition of alkylphosphine, which is known as an L-type ligand, improved the PL efficiency only by 20%, the use of metal halides, which are categorized as Z-type ligands, demonstrated a twofold to threefold improvement of the PL quantum yield, with the highest value reaching 73.4%. The same procedure was applied to the band-edge emitting core/shell-like QDs that were synthesized in one batch based on our previous findings. While the as-prepared core/shell-like QDs exhibited a PL quantum yield of only 9%, the PL quantum yield increased to 49.5% after treatment with metal halides.