Facet‐Specific Ligand Interactions on Ternary AgSbS₂ Colloidal Quantum Dots

Abstract

Silver dimetal chalcogenide (Ag-V-VI ) 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 AgSbS 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.

The Surface Chemistry and Structure of Colloidal Lead Halide Perovskite Nanocrystals

“…Approximately 20% of the atoms in a 10 nm CsPbBr3 nanocrystal are within the first surface layer of the particle. The surface chemistry of semiconductor nanocrystals is affected by their exposed crystal facets, 17,18 stoichiometry, 19,20 organic ligands, [21][22][23] and ionicity. [24][25][26] Unlike more covalent semiconductor nanocrystals (e.g., CdSe, InP), lead halide perovskites are markedly ionic, which affects their environmental stability, 27 electronic structure and defect tolerance, 28 and ligand binding and fluxionality.…”

Improved Eco-Friendly Photovoltaics Based on Stabilized AgBiS2 Nanocrystal Inks

“…9,23,40,41 Hence, we sought to use AgI-and BiI 3 -based halometallates such as [AgI 2 ] − /[Ag] + and [BiI 4 ] − / [BiI 2 ] + in the SPLE of AgBiS 2 NCs. BiI 3 is soluble in DMF, the polar aprotic solvent used in this SPLE, but AgI is not.…”

Efficiency Limit of Colloidal Quantum Dot Solar Cells: Effect of Optical Interference on Active Layer Absorption

“…At this scale, both Mie and Rayleigh scattering in the visible and infrared light range rarely occur because of the low scattering coefficient . It has been shown that at a larger length scale, the effective light path and thus the current density can increase from enhanced scattering and light trapping. − Also, the textured ZnO showed depletion width and diffusion length in PbS CQD solar cell structures similar to that of the flat ZnO nanoparticle layer, confirming a similar collection efficiency in each device (Figure S1). Using this experimental design, J SC was calculated from external quantum efficiency (EQE) of solar cells with thicknesses of the PbS CQD films varying from 200 to 800 nm (Figure ).…”