Bernard Nghiem

Transparent conducting oxides superstrate for thin film solar cells: an industrial prospective

The demand for a TCO coated glass substrate as a base material and front electrode of the solar cells is expected to grow very strongly in the next few years. Therefore it is crucial to prepare the industrial tools and proper glass compositions to meet this very impressive demand. Mass production of extra clear glass and atmospheric pressure thermal CVD tool installed directly on the float glass line are adapted processes to mass produce in a cost effective way fluorine doped tin oxide based TCO superstrates for PV application. From an industrial prospective, opto electrical trade off is an important issue. But maintaining the performances of the electrode during 20 years of function is a major concern too. In this paper, we will underline the durability issue of the SnO2 : F based electrode and specifically, electrochemical corrosion phenomenon due to electrical field assisted diffusion of alkaline ions from the glass toward the interface between the glass substrate and the TCO film. The DC electrical field responsible for this phenomenon is due to the difference of potentials between the grounded metallic frame of the PV modules and the TCO electrodes which are strongly negatively biased.