Amorphous Alumina Film Robust under Cyclic Deformation: a Highly Impermeable and a Highly Flexible Encapsulation Material

Abstract

The lack of highly impermeable and highly flexible encapsulation materials is slowing the development of flexible organic solar cells. Here, a transparent and lowtemperature synthetic alumina single layer is suggested as a highly impermeable and a highly flexible encapsulation material for organic solar cells. While the water vapor transmission rate (WVTR) is maintained up to 100,000 bending cycles for a 25 mm bending radius (corresponding to 8.1% of the elastic deformation limit), as measured by in situ tensile testing with free-standing 50 nm-thick alumina films, the WVTR degraded gradually depending on the bending radius and bending cycles for bending radii less than 25 mm. The degradation of the WVTR in cyclic deformation within the elastic deformation limit is investigated, and it is found to be due to the formation of pinholes by a bond-switching mechanism. Also, encapsulated organic solar cells with alumina films are found to maintain 80% of initial efficiency for 2 weeks even after cyclic bending with a 4 mm bending radius.

Highly Efficient Self-Encapsulated Flexible Semitransparent Perovskite Solar Cells via Bifacial Cation Exchange

“…Similarly, excellent mechanical robustness was obtained for the PI@GR-based device under prolonged mechanical stresses of up to 10 000 bending cycles at a radius of 5 mm (Figure f). In thin-film encapsulation, the WVTR can be significantly degraded by defect-induced mechanical stresses owing to the low elastic limit and catastrophic failure of thin films with pre-existing internal defects. , Thus, we examined the moisture stability of the flexible ST-BCE-PSC under 25 °C and 85% RH conditions after 10 000 bending cycles at a radius of 5 mm. As shown in Figure S11, the device still showed outstanding operational stability similar to the results shown in Figure f.…”

Highly Elastic and Corrosion-Resistive Metallic Glass Thin Films for Flexible Encapsulation

“…In general, the encapsulation performance of amorphous oxide materials degrades after cyclic deformation because of the formation of nanoscale defects. 54,55 However, the encapsulation performance of the ternary metallic glass thin film is maintained even after cyclic bending because of its high structural stability. Figure 4a shows a schematic of flexible organic solar cell used in this study for encapsulation.…”

“…The patterned mask used during the evaporation has an area of 0.04 cm 2 . 55,56 Encapsulation of Organic Solar Cells. For encapsulation of organic solar cells, 260 nm thick ternary metallic glass is deposited on a 125 μm thick flexible PET substrate.…”

Complete stress release in monolayer ALD-Al2O3 films based on mechanical equilibrium homeostasis to realize a bending radius of 1 mm

“…If the ALD-Al 2 O 3 monolayer film has better flexibility to achieve independent flexible encapsulation performances, it would undoubtedly reduce the preparation process and realize ultra-flexible optoelectronic devices. 25–27…”

“…If the ALD-Al 2 O 3 monolayer film has better flexibility to achieve independent flexible encapsulation performances, it would undoubtedly reduce the preparation process and realize ultra-flexible optoelectronic devices. [25][26][27] In this study, foldable ALD-Al 2 O 3 films with low residual stresses and high water-vapor-barrier properties were fabricated.…”