Encapsulation of flexible organic solar cells via parylene and alumina dyads

Abstract

Robust encapsulation is indispensable for flexible organic solar cells (OSCs) moving into practical applications because the materials and interfaces of the cells are susceptible to water vapor and oxygen under illumination. Fleixble barrier films are one of the key parts of the encapsulation. In this work, we report the fabrication of flexible barrier films comprising of alternating parylene C and alumina dyads, and the application of these barrier films to encapsulate flexible OSCs. Parylene C layers are deposited by chemical vapor deposition (CVD) and dense alumina layers are grown by atomic layer deposition (ALD). The fabricated film comprising of three dyads of parylene C and alumina shows a low water vapor transmission rate (WVTR) of 8.7 × 10⁻⁴ g m⁻² day⁻¹ (25 °C, 100% RH) devrived by calcium conductance test. Encapsulated OSCs could retain 80% of their initial efficiency after immersed into water for 624 h, and could retain 81% of their initial efficiency under continuous illumination for 1156 h in ambient atmosphere.