We investigated different moisture barrier layers, including inorganic Al₂O₃ films and six multilayer (dyad) barriers combined with an organic parylene C polymer. These dyads with varying thicknesses (i.e., 1-dyad, 2-dyad, and 3-dyad) were prepared on a polyethylene naphthalate (PEN) substrate. A single Al₂O₃ film on a PEN with an optimal thickness of 70 nm effectively acted as a moisture barrier. The measured water vapor transmission rate (WVTR) was 9.64 × 10⁻² g/m²/day. Furthermore, a 2-dyad barrier, comprising an Al₂O₃ layer (70 nm) paired with parylene (700 nm), exhibited an even lower WVTR of 2.01 × 10⁻⁴ g/m²/day. We employed a 2-dyad barrier to laminate a flexible photovoltaic (PV) cell and assessed its performance under damp heat conditions of 85 ^∘C and 85 % relative humidity. After undergoing a damp heat test for 500 h, the PV module exhibited a light conversion efficiency of 18.25 %, which is only 2.8 % lower than that of the initial module. The 2-dyad barrier composed of Al₂O₃-parylene layers has been demonstrated to be highly effective in preventing moisture penetration. Thus, it is an excellent encapsulation layer for the fabrication of flexible solar modules.

Keywords: Moisture barrier, Organic-inorganic dyad, Water vapor transmission rate, Solar cell encapsulation, Damp heat test