This contribution, based on literature review, presents a general overview of properties and applications of transparent conductive oxides, TCO. The requested properties of TCO are a high conductivity associated to high transparency in a wide wavelength range. The relation between the techniques used for deposition or growing TCO and the possibility of their doping with appropriate dopant and concentration were discussed relatively to their applications and properties. Thus, we present in this part, the various possible techniques for growing TCO and discuss the effect of the temperature on the functional properties. This self-consistent presentation is also considered to introduce a better understanding of the expected requirements for TCO integrated as transparent electrodes in photovoltaic cells and modules. These developments of TCO for photovoltaic applications will be presented in a second publication.

This contribution is the second part of a presentation of transparent conductive oxides, TCO. After a general overview in the first publication of properties and applications of TCO related to the type of oxide and dopant, the growth techniques and the temperature, we focus in the current one on three families of TCO used as transparent electrodes in photovoltaic, PV, cells and modules. Indeed, new generations of solar cells need optimizing TCO with improved conductivity and transparency depending on substrate, type of PV cells, and conditions of used. Thus, ITO, ZnO-AZO, and SnO2-FTO TCO families are considered. ITO presents the best combination of electrical and optical properties but TCO based on the two other families are challenging in many photovoltaic applications for obtaining low cost and environmental friendly electrodes with comparable performances. Due to the high number of publications on TCO for PV applications, this contribution does not claim to be exhaustive but makes it possible to summarize the main information concerning these materials by approaching them in a common methodology.

Transparent conductive oxides are materials combining great transparency with high conductivity. In photovoltaic applications, they are developed under thin layer for the realization of upper electrodes of solar cells. Among transparent oxide materials, Zinc Oxide (ZnO) presents unique properties, starting with its first qualities to be abundant, low-cost and non-toxic oxide. Zinc Oxide thin film was deposited on rectangular glass substrate by magnetron sputtering. After an overview of the properties expected for good transparent conductive materials, the effect of distance from the center of the cell on the morphology of the film was investigated by Atomic Force Microscopy (AFM). The scanning was done on different area of the sample as function of the distance from the central position of the direct sputtering jet. As far as the distance increased, it has been noticed a quasi-linear increase in thickness of the ZnO deposited film and a change in the grain shape from spherical to pyramidal with an increase in the size of the particles. Controlling the sputtering distance allows the control of texture, thus of the Haze factor, the photo-generation of excitons, as well the optical transmission of the TCO layer and finally an improvement in the efficiency of the so-built photovoltaic cells.