High Figure of Merit Indium-Tin Oxide (ITO) Electrodes Based on Metal-Polymer Composites without Counter Anions

In solution-based polymer-assisted deposition (PAD), high performance transparent conducting oxides (TCO) have been rarely reported compared to multicomponent inorganic thin films (metal-oxides, -carbides, -nitrides, and -chalcogenides). TCO fabrication requires i) removal of impurities, ii) high-density oxide film, iii) homogeneity in crystal structures and film morphology, and iv) controllable elemental doping. This study carries out a systematic investigation into preparation of stable multicomponent metal-polymer complex solutions by removing the counter anions in the solution. This study also performs accurate acid-base titration for each metal species in order to optimize the amount of PEI, thus maximize the density of the film. As a representative TCO, Sn-doped In₂O₃ (ITO) films have been fabricated. The ITO film has an excellent sheet resistance (24.5 Ω/sq), high transparency (93%), and a figure of merit of 2.1 × 10^-2 Ω^-1, which are comparable to the best.