Characteristics of Moisture Barrier Layer of Al₂O₃-Parylene Dyad Structure for Use as Solar Cell Encapsulant

We investigated different moisture barrier layers, including inorganic Al 2 O 3 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 Al 2 O 3 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/m 2 /day.Furthermore, a 2-dyad barrier, comprising an Al 2 O 3 layer (70 nm) paired with parylene (700 nm), exhibited an even lower WVTR of 2.01 × 10 -4 g/m 2 /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 Al 2 O 3 -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.