Optical and electrical properties of ink-jet printed indium–tin-oxide nanoparticle films

In this work, spherical indium tin oxide (ITO) nanoparticles (~ 15 nm) synthesized by co-precipitation method were successfully applied for direct ink-jet printing of transparent conducting patterns on polyethylene terephthalate substrates. The printed ITO nanoparticle patterns with various thicknesses were investigated for understanding fundamental properties and potentials for soft electronics. It has been found that the optical transmittance in the visible region as well as the band-gap absorption edge of the printed ITO films significantly varies with thickness, which is related to the huge nanoparticle scattering effect as evidenced. The electrical resistivity can be effectively improved by increasing the pattern thickness, indicating that the present printed ITO films are of great potential for optoelectronic applications. ► ITO nanoparticles are prepared for direct ink-jet patterning on flexible substrates. ► Repeated printing cycles with diluted ink are effective for dynamic thickness control. ► Scattering effects dominate the optical transmittance and UV–visible spectra profile. ► The electrical conductivity is significantly improved up to a critical thickness.