Zero reduction luminescence of aqueous-phase alloy core/shell quantum dots via rapid ambient-condition ligand exchange

Thanh-Hai Le; Semin Kim; Subin Chae; Yunseok Choi; Chul Soon Park; Eunseo Heo; Unhan Lee; Hyungwoo Kim; Oh Seok Kwon; Won Bin Im; Hyeonseok Yoon

doi:10.1016/j.jcis.2019.12.104

Zero reduction luminescence of aqueous-phase alloy core/shell quantum dots via rapid ambient-condition ligand exchange

J Colloid Interface Sci. 2020 Mar 22:564:88-98. doi: 10.1016/j.jcis.2019.12.104. Epub 2019 Dec 27.

Authors

Affiliations

¹ Department of Polymer Engineering, Graduate School, Chonnam National University, 77 Yongbong-ro, Gwangju 61186, South Korea.
² Alan G. MacDiarmid Energy Research Institute, School of Polymer Science and Engineering, Chonnam National University, 77 Yongbong-ro, Gwangju 61186, South Korea; Department of Polymer Engineering, Graduate School, Chonnam National University, 77 Yongbong-ro, Gwangju 61186, South Korea.
³ Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Daejeon 34141, South Korea; Department of NanoBiotechnology, Korea University of Science and Technology (UST), 125 Gwahak-ro, Daejeon 34141, South Korea. Electronic address: oskwon79@kribb.re.kr.
⁴ Division of Materials Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, South Korea. Electronic address: imwonbin@hanyang.ac.kr.
⁵ Alan G. MacDiarmid Energy Research Institute, School of Polymer Science and Engineering, Chonnam National University, 77 Yongbong-ro, Gwangju 61186, South Korea; Department of Polymer Engineering, Graduate School, Chonnam National University, 77 Yongbong-ro, Gwangju 61186, South Korea. Electronic address: hyoon@chonnam.ac.kr.

PMID: 31911231
DOI: 10.1016/j.jcis.2019.12.104

Abstract

Quantum dots (QDs) have been widely studied as promising materials for various applications because of their outstanding photoluminescence (PL). Although ligand exchange methods for QDs have been developed over two decades, the PL quantum yield (QY) of aqueous phase QDs is still lower than that of their organic phase and the mechanism of quenching has not been clearly understood. In this study, we demonstrate for the first time that 3-mercaptopropionic-capped CdZnSeS/ZnS core/shell QDs obtained via ligand exchange in a ternary solvent system containing chloroform/water/dimethyl sulfoxide can enable the fast phase transfer and zero reduction of PL under ambient condition. The new solvent system allows the ligand-exchanged QDs to exhibit enhanced QYs up to 8.1% of that of the organic-phase QDs. Based on both theoretical calculation and experiment, it was found that control over the physical/chemical perturbation between the organic/aqueous phases by choosing appropriate solvents for the ligand exchange process is very important to preserve the optical properties of QDs. We believe that our new technologies and theoretical knowledge offer opportunities for the future design and optimization of highly stable and highly luminescent aqueous-phase QDs for various applications.

Keywords: Ligand exchange; Photoluminescence; Quantum dots; Quenching; Surface modification.