Modelling water vapour permeability through atomic layer deposition coated photovoltaic barrier defects

Mohamed Elrawemi, Liam Blunt, Leigh Fleming, David Bird, David Robbins, Francis Sweeney

Research output: Contribution to journalArticle

8 Citations (Scopus)


Transparent barrier films such as Al2O3 used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance.

Original languageEnglish
Pages (from-to)101-106
Number of pages6
JournalThin Solid Films
Issue numberPartA
Publication statusPublished - 3 Nov 2014


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