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Ethanolamine-assisted low-temperature crystallization of hydroxide nanoparticle ink into transparent and conductive ITO layers

Liu, Yujing, Moser, Thierry, Andres, Christian, Gorjan, Lovro, Remhof, Arndt, Clemens, Frank, Graule, Thomas, Tiwari, Ayodhya N., Romanyuk, Yaroslav E.
Journal of materials chemistry A 2019 v.7 no.7 pp. 3083-3089
absorption, crystallization, ethanolamine, indium, moieties, nanoparticles, tin, transmittance, wavelengths
Low-temperature crystallization is desired for achieving solution processable transparent conductive oxide (TCO) layers. Here we demonstrate a low-temperature crystallization of tin doped indium oxide (ITO) layers by taking preformed indium-tin hydroxide nanoparticles as the precursor and applying surface modification with ethanolamine on the as-prepared layers. Surface modification with ethanolamine is shown to speed up the dehydration of the hydroxide precursor, resulting in earlier onset of crystallization into the cubic bixbyite ITO phase with a larger crystal size. The ethanolamine-modified ITO nanoparticle layer possesses fewer surface hydroxyl groups as compared to the non-treated layer, corresponding to a higher charge carrier concentration, as manifested in a near IR absorption. The nanoparticle ITO layer shows dc conductivity two times higher than that of the non-treated layer. A conductivity of 43 S cm⁻¹ combined with a high optical transmittance of above 90% in the 380–1100 nm wavelength range is obtained for the nanoparticle ITO layer annealed at 300 °C.