Microwave-assisted synthesis of indium tin oxide nanocrystals in polyol media and transparent, conductive layers thereof

Aiming at a facile and low-cost liquid phase synthesis of indium tin oxide (ITO), a microwave-assisted preparation in high-boiling, multidentate alcohols (so-called polyols) is evaluated. While heating for 2 h at 200 °C and ambient pressure, transparent ITO suspensions are obtained exhibiting a bright blue color. According to dynamic light scattering, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Brunauer–Emmett–Teller analysis, as-prepared particles turn out to be single crystalline with an average diameter of 17 nm and a near monodisperse size distribution. Four-point probing of powder pellets reveals a low resistivity (1.1 × 10− 2 Ω cm) of as-prepared In2O3:Sn (5 mol.%). Fourier-transform infrared spectra show a reflectivity in the infrared close to 100%. As a proof of concept, thin layers are deposited on glass plates using a simple solvent evaporation technique. After a certain post-treatment, these layers exhibit a visible transmittance similar to the uncoated glass substrate and a low resistivity (1.2 × 10− 2 Ω cm).