A Novel Approach for the Development of Moisture Encapsulation Poly(vinyl alcohol-co-ethylene) for Perovskite Solar Cells

[Image: see text] 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.