Facet‐Specific Ligand Interactions on Ternary AgSbS2 Colloidal Quantum Dots

• Published in: Chemistry : a European journal Vol. 23; no. 70; pp. 17707 - 17713
• Main Authors: Choi, Hyekyoung, Kim, Sungwoo, Luther, Joseph M., Kim, Sang‐Wook, Shin, Dongwoon, Beard, Matthew C., Jeong, Sohee
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 14.12.2017
• Subjects: Absorptivity; AgSbS2; Chalcogenides; Chemical analysis; Chemistry; Crystal lattices; Crystal structure; Devices; Energy gap; I–V–VI2; Lead free; Ligands; Optoelectronic devices; Oxidation; Performance enhancement; Photonic band gaps; Protective coatings; Quantum dots; Silver; Sulfur; Surface chemistry; ternary
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201703681

Silver dimetal chalcogenide (Ag‐V‐VI2) ternary quantum dots (QDs) are emerging lead‐free materials for optoelectronic devices due to their NIR band gaps, large absorption coefficients, and superior electronic properties. However, thin film‐based devices of the ternary QDs still lag behind due to the lack of understanding of the surface chemistry, compared to that of lead chalcogenide QDs even with the same crystal structure. Herein the surface ligand interactions of AgSbS2 QDs, synthesized with 1‐dodecanethiol used as a stabilizer, are studied. For nonpolar (1 0 0) surfaces, it is suggested that the thiolate ligands are associated with the crystal lattices, thus preventing surface oxidation by protecting sulfur after air‐exposure, as confirmed through optical and surface chemical analysis. Otherwise, silver rich (1 1 1) surfaces are passivated by thiolate ligands, allowing ligand exchange processes for the conductive films. This in‐depth investigation of the surface chemistry of ternary QDs will prompt the performance enhancement of their optoelectronic devices. Ternary AgSbS2 colloidal quantum dots show that the lattice‐associated thiolates on (1 0 0) surfaces prevent the surface oxidation and the anionic thiolates on Ag‐rich (1 1 1) surfaces allow for the preparation of conductive films through effective ligand exchange processes.