Influence of Thermal Annealing on the Microstructural Properties of Indium Tin Oxide Nanoparticles

Abstract

In this work, we studied the microstructural changes of ITO during the annealing process. ITO nanoparticles were prepared by the sol-gel method using indium tin hydroxide as the precursor. The prepared sample was investigated using TEM, powder XRD, XPS, DRIFT, and 2D correlation analysis. The O 1s XPS spectra suggested that the microstructural changes during the annealing process are closely correlated with the oxygen sites of the ITO nanoparticles. The temperature-dependent in situ DRIFT spectra suggested that In-OH in the terminal sites is firstly decomposed and, then, Sn-O-Sn is produced in the ITO nanoparticles during the thermal annealing process. Based on the 2D correlation analysis, we deduced the following sequence of events: 1483 (due to In-OH bending mode) → 2268, 2164 (due to In-OH stretching mode) → 1546 (due to overtones of Sn-O-Sn modes) → 1412 (due to overtones of Sn-O-Sn modes) cm −1.

Fabrication of Highly Transparent and Conductive Indium–Tin Oxide Thin Films with a High Figure of Merit via Solution Processing

“…As shown in Figure A, there are several absorption bands below 1000 cm –1 assigned to the vibrations of SnO 2 lattice. The strong absorption bands around 1533 and 1421 cm –1 are attributed to the overtones of the asymmetric Sn–O–Sn modes, as observed in the in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) during the annealing process of ITO hydroxide precursor from 80 to 360 °C . The intensities of these two peaks increase with the increment of annealing temperature above 240 °C, where the hydroxide precursor starts to form ITO nanocrystals.…”

“…The strong absorption bands around 1533 and 1421 cm −1 are attributed to the overtones of the asymmetric Sn−O−Sn modes, 42 as observed in the in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) during the annealing process of ITO hydroxide precursor from 80 to 360 °C. 43 The intensities of these two peaks increase with the increment of annealing temperature above 240 °C, where the hydroxide precursor starts to form ITO nanocrystals. The corresponding assignments are listed in Table 2 on the basis of reported references.…”

“…The intensities of these two peaks increase with the increment of annealing temperature above 240 °C, where the hydroxide precursor starts to form ITO nanocrystals. The corresponding assignments are listed in Table on the basis of reported references. − The two peaks at 1340 and 1023 cm –1 without assignment remain after drying the pellet under vacuum at 80 °C for 72 h, arising from the product upon hydrolysis, not the residual ethanol.…”