Alq3/MgF2 Multilayered Encapsulation Film for Enhanced Stability of Perovskite Solar Cells

Abstract

Environmental factors such as oxygen and moisture are known to severely degrade perovskite solar cells (PSCs). In general, rigid glasses and resins are used to prevent moisture penetration. However, typical encapsulation exhibits the disadvantage of being vulnerable to external physical impact. In this study, to minimize device degradation from environmental factors, we present the organic/inorganic multilayered encapsulation film (MEF) that can effectively block moisture and oxygens. Tris (8-hydroxyquinolinato) aluminum (Alq3) and magnesium fluoride (MgF2) were used as an organic and inorganic layer in the MEF structure, respectively. The optimal condition for effective encapsulation exhibits the 5 pairs of Alq3/MgF2 structure and the water vapor transmission rate (WVTR) of the MEF is measured about 0.2635 g/m2 per day. The PSCs integrated with MEF show remarkable moisture barrier performance compared to the PSC without MEF (bare PSCs). After 12 days of degradation, the PSCs with MEF shows 40% degradation in terms of a power conversion efficiency (PCE), while the degradation rate of PCE of the bare PSCs shows 72.7% loss in PCE. Moreover, the change of the perovskite film absorbance under the film degradation provides the superior encapsulation characteristics of MEF. By investigating the changes in the photovoltaic parameters and water vapor transmission rate of MEF, we confirm that the moisture barrier performance of the MEF improved the stability of PSCs.