Instant Postsynthesis Aqueous Dispersion of Sb-Doped SnO₂ Nanocrystals: The Synergy between Small-Molecule Amine and Sb Dopant Ratio

Abstract

Direct printing of transparent conducting oxide (TCO) nanocrystal dispersions holds great promise in solution-processed optoelectronics due to its advantages of low material waste and direct patterning on substrates. An essential prerequisite for printable TCO colloidal solutions is the effective stabilization of TCO nanocrystals to prevent their strong aggregation. In situ stabilization uses long-chain ligands to provide interparticle steric repulsion between TCO nanocrystals during the growth of TCO nanocrystals. In sharp contrast, the postsynthesis dispersion of TCO nanocrystals is particularly challenging since the agglomeration already occurs, especially for TCO nanocrystals synthesized without protection by any organic species. Herein, we propose an instant postsynthesis strategy for aqueous colloidal dispersions of Sb-doped SnO2 (ATO) nanocrystals using small-molecule amines of propylamine, ethylenediamine, monoethanolamine, and triethylamine. The average size of ATO secondary particles in aqueous dispersions can be instantly reduced from around 400 to about 25 nm using these amines. The increased Sb dopant ratio also plays a synergistic role in the dispersion effect. The small-molecule amines are found to be preferably adsorbed onto the Sb sites exposed on ATO nanocrystal surface. A higher Sb dopant ratio would facilitate the adsorption of more amines and induce stronger surface charge repulsion that benefits the stable dispersion of ATO nanocrystals. TCO films fabricated with the ATO nanocrystal dispersions have a high transparency of 80.6% and low sheet resistance of 492 Ω/sq, showing promising application in electrochromic devices.

Ligand Tuning of Localized Surface Plasmon Resonances in Antimony-Doped Tin Oxide Nanocrystals

“…For instance, the NCs from a batch with a nominal Sb concentration of 20% exhibit a mean size of 5.3 ± 1.3 nm, as manually evaluated from the transmission electron microscopic images. As also found previously [16], the NC size slightly increased for batches with a lower antimony content, and their size distribution became broader (up to 7.1 ± 1.6 nm for undoped SnO2 NCs) (Figure 1c). The elemental compositions of the NCs were evaluated by EDX analysis within several areas of drop-casted ATO (TO) layers prepared on Si substrates (Table S1).…”

“…Recently invented fluoride and indium co-doped cadmium oxide [13] LSPR NCs are less indium consuming, but will presumably fail in meeting the RoHS requirements because even the current exceptions for cadmium (e.g., solar PV modules) are questionable to be renewed. Owing to the cheapness, facile processes of syntheses, and plasmonic properties closely matching the ITO materials, antimony-doped tin oxide (ATO) is a perfect substitute for the applications described above [14][15][16]. Despite belonging to an ultra-wide bandgap semiconductor class, tin dioxide (TO) possesses good thermal conductivity and carriers' mobility; the aliovalent and self-doping of TO offers the opportunity for efficient carrier concentration control [17].…”

Crystallographic‐Site‐Specific Structural Engineering Enables Extraordinary Electrochemical Performance of High‐Voltage LiNi0.5Mn1.5O4 Spinel Cathodes for Lithium‐Ion Batteries

“…The coexistence of both ions in the structure was further confirmed by Sb 3d 3/2 X-ray photoelectron spectroscopy (XPS) (Figure 2b), where spectral peaks at 539.4 and 540.8 eV are assigned to Sb 3+ and Sb 5+ , respectively. [29,30] It is known that XPS is a surface-sensitive technique with a penetration depth of less than 20 nm. The ratio of Sb 3+ to Sb 5+ determined by the peak area is 83:17, giving an average valence of +3.4 at the particle surface.…”

Solvothermal synthesis of soluble, surface modified anatase and transition metal doped anatase hybrid nanocrystals

“…[24][25][26] This approach offers exceptional exibility, both chemicallysimple wet-chemical techniques permit the synthesis of a wide range of compositionsand physically, as dispersions of preformed colloidal nanocrystals may be used to coat at substrates, irregularly shaped objects or may be used to generate supported catalysts or composites and gels. [27][28][29][30][31][32] There has been a growing research effort in this eld, such that dispersible nanocrystals of TiO 2 , SnO 2 , CeO 2 , ZnO, MnO, and others have been accessed by methods including non-aqueous sol-gel synthesis, solvothermal/ hydrothermal synthesis, hot-injection, and thermolysis. 13,29,[32][33][34][35][36][37] Previously we have reported on the production of highly dispersible tin oxide and titanium oxide nanocrystals by post-synthetic modication of hydrous oxide precursors.…”