Environmental stability of highly conductive nominally undoped ZnO layers

Abstract

Abstract-Highly conductive nominally undoped ZnO (b-ZnO) films represent an attractive alternative for ZnO:Al windows employed in thin film solar cells. In order to assess their suitability for the PV industry, we examine here their stability in various environments. We show that the b-ZnO films can exhibit comparable stability to ZnO:Al films in both ambient and heated air. However, b-ZnO films degrade faster in accelerated open damp heat (DH) conditions, which can be related to their columnar microstructure. Finally, a b-ZnO multilayer coating with an improved environmental stability is presented.

Improved environmental stability of highly conductive nominally undoped ZnO layers suitable for n-type windows in thin film solar cells

“…2 in Ref. [22]. The broadening of the θ θ − 2 ZnO 002 diffraction peaks suggested that the thinner b-ZnO films possess a lower X-Ray coherence length, d XRD , as also depicted here in the legend of Fig.…”

“…It is to be underlined, that the optoelectrical properties of this b-ZnO stack are not significantly compromised by the overlayer presence [28], while its environmental stability is substantially improved. This is witnessed by the dry heat ageing experiments [22], and by the open DH analyses of unencapsulated solar cells equipped with the b-ZnO multilayers that are discussed in the next section. .…”