Strategies for novel transparent conducting sol–gel oxide coatings

Abstract Transparent conducting coatings of doped SnO 2 and Zn 2 SnO 4 have been deposited by the sol–gel technique on borosilicate and alumosilicate glass substrates, respectively. As films of SnO 2 : Sb (ATO) show some intrinsic drawbacks, which are discussed in this report, alternative dopants for SnO 2 such as Ta, Nb and W, were examined concerning the electrical and optical properties of the deposited coatings. In this way, coatings with resistivities on the order of 3 × 10 − 2 Ω cm characterized by much higher charge carrier mobilities than for SnO 2 : Sb and a transmission of > 85% were realized. In the search for ternary compounds (A x B y O z ), coatings in the system ZnO–SnO 2 were examined, focusing on the fabrication of meta zinc stannate (Zn 2 SnO 4 ). Coatings made from tin alkoxides yielded monophasic materials with high crystallinity and good morphological properties. By post-annealing, a resistivity of 0.4 Ω cm with charge carrier mobilities of up to 7 cm 2 /Vs were obtained. Therefore, the development of the coating solution is as crucial as the elaboration of the heat treatment procedure of as-deposited films in order to obtain pure Zn 2 SnO 4 phase coatings without any impurity phases.