A method for enhancing the moisture barrier property of polydimethylsiloxane (PDMS) polymer films is proposed. This is achieved by filling the PDMS free volume with aluminum oxide (AlOx).

In this study, we developed the universal encapsulation method using poly(vinyl alcohol- co -ethylene) (EVOH) to improve the water stability of perovskite solar cells. In order to enhance the moisture barrier property, we utilized SiO 2 and graphene oxide (GO) fillers in the EVOH matrix. First, UV-treated SiO 2 increased the dispersibility in the EVOH matrix and made the penetrating path more complicated, which led to a better moisture barrier property. The water vapor transmission ratio (WVTR) is enhanced from 4.72 × 10 –2 (EVOH only) to 1.55 × 10 –2 (EVOH with SiO 2 filler) g/m 2 day. Second, we found that GO reduce the unreacted hydroxyl groups that could attract water molecules at the surface of EVOH. The addition of GO increased the WVTR up to 3.34 × 10 –3 g/m 2 day. Finally, our EVOH-based film successfully encapsulated without the efficiency drop. The encapsulated devices surprisingly maintained 86% of their performance even under direct contact with water for 5 h.

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