(172f) Formation of Thin Films of IZO and ITO Nanoparticles

Nanoparticulate thin films are of high interest in various industries. In this contribution we focus on electronic applications as conducting layers in solar cells or displays [1]. The properties of these solution processed films are varying from highly porous to very densely packed films according to their field of application. We present our work on transparent conductive oxide films of indium tin oxide nanoparticles (ITO) [2] which were prepared in the gas phase and indium zinc oxide nanoparticles (IZO) produced by wet chemical sol-gel synthesis. Both are dispersed in alcoholic solutions in order to deposit the particles by spin- and dip-coating on silica wafers and glass substrates. The stability of the dispersions is verified by either dynamic light scattering (DLS) or UV-vis spectroscopy. Analytical tools for investigation of morphology, surface and conductivity of the thin films were AFM, XRD, SEM, HRTEM, four-point probe measurements and impedance spectroscopy. The effects of the indium concentration in the IZO films on the morphology, the optical and electrical properties of the thin films were investigated. Moreover, the influence of the layer thickness and annealing temperature on the film properties are discussed. The ITO and IZO films deposited on glass substrates showed a high transparency in the visible range of at least 80% to 95%. With the ITO thin nanoparticulate films we achieved conductivities up to 120 Scm^-1 simply by varying preparation conditions [3] and up to 196 Scm^-1 with a treatment in forming gas [2], the latter being the best known value of ITO particles produced in the gas phase. IZO dispersions were stable over at least two months. With IZO nanoparticulate thin films we achieved conductivities up to 104 S/cm^-1 by forming gas treatment of the films.

[1] R. Marczak, F. Werner, J.-F. Gnichwitz, A. Hirsch, D.M. Guldi, W. Peukert, Journal of Physical Chemistry C, 113 (2009) 4669-4678.

[2] M. Mahajeri, M. Voigt, R.N. Klupp Taylor, A. Reindl, W. Peukert, Thin Solid Films, 518  3373-3381.

[3] A. Reindl, M. Mahajeri, J. Hanft, W. Peukert, Thin Solid Films, 517 (2009) 1624-1629.