Comparison of ITO/metal/ITO and ZnO/metal/ZnO characteristics as transparent electrodes for third generation solar cells

In this paper we present the physical properties of two types of multilayer structures: ITO/metal/ITO and ZnO/metal/ZnO obtained by successive sputtering depositions of metallic targets (In:Sn, Zn, Ag, Au) in reactive atmosphere (for oxide films) and under inert atmosphere (for metallic interlayer films). Very good quality transparent conducting thin films structures (ρ=2×10−5 Ω cm, T∼90%) were obtained. The morphological, optical and electrical properties were analyzed and compared for the multilayer films deposited in identical conditions on glass and PET substrates. The influence of substrate nature on the morphological properties is more pronounced in the case of zinc oxide films. The Haake figures of merit at λ=550 nm are comprised between 4×10−3 Ω−1 and 29×10–3 Ω−1 in function of the nature of the metallic interlayer. The stability of electrical properties with the temperature of the oxide/metal/oxide films is remarkable in comparison with the usual behavior of single oxide films.

► ITO/metal/ITO and ZnO/metal/ZnO multilayer structures were deposited on glass and PET substrates.
► Structural, morphological, electrical and optical properties are studied and compared.
► The roughness is more important in the case of films deposited on PET substrates.
► The stability of the electrical resistivity with the temperature is remarkable.