Design of Highly Water Resistant, Impermeable, and Flexible Thin-Film Encapsulation Based on Inorganic/Organic Hybrid Layers

Abstract

The lack of a transparent, flexible, and reliable encapsulation layer for organic-based devices makes it difficult to commercialize wearable, transparent, flexible displays. The reliability of organic-based devices sensitive to water vapor and oxygen must be guaranteed through an additional encapsulation layer for the luminance efficiency and lifetime. Especially, one of the major difficulties in current and future OLED applications has been the absence of thin-film encapsulation with superior barrier performance, mechanical flexibility, and water-resistant properties. In this work, we fabricated highly water-resistant, impermeable, and flexible inorganic/organic multilayers with optimized Al2O3 and functional organic layers. The key properties of the fabricated multilayers were compared according to the thickness and functionality of the inorganic and organic layers. Improvement of the barrier performance is mainly attributed to the optimized thickness of the Al2O3 films, and is additionally due to the increased lag time and effective surface planarization effects caused by the use of micrometer-thick organic layers. As a result, the 3-dyad multilayer structure composed of 60-nm-thick Al2O3 layers deposited at 70 °C and 2-μm-thick silane-based inorganic/organic hybrid polymer (silamer) layers with layered silica exhibited the lowest WVTR value of 1.11 × 10-6 g/m2/day in storage conditions of 30°C/90% relative humidity. In addition, the multi-barrier exhibited good mechanical stability through the use of alternating stacks of brittle inorganic and soft organic layers, without showing a large increase in the WVTR after bending tests. In addition, silamer layers improved the environmental stability of the Al2O3 ALD film. The silamer layer coated on the Al2O3 film effectively worked as a protective layer against harsh environments. The effective contact at the interface of Al2O3/silamer makes the barrier structure more impermeable and corrosion-resistant. In this study, we not only demonstrated an optimized multilayer based on functional organic layers, but also provided a methodology for designing a wearable encapsulation applicable to wearable organic electronics.

Multi-directionally wrinkle-able textile OLEDs for clothing-type displays

“…The gas barrier and the OLED were deposited on the textile platform, and the liquid passivation on which the gas barrier had formed was laminated to the OLED. The gas barrier that functioned as the OLED encapsulation to block moisture and oxygen 31 was fabricated using a spacer polymer 32,33 and the nano-stratified barrier of Al 2 O 3 and ZnO quasi-films [34][35][36][37][38] . The porous and defect-decoupling characteristics of the nanostratified structure enhanced the structural flexibility and barrier property.…”

Atomic layer deposition for quantum dots based devices

“…It is suitable to grow high-quality dielectric and semiconductor on different substrate even including the porous and high-aspect ratio substrates [39][40][41][42] , which has been widely used in areas of thin film solar cell, photodetectors and other electronic devices [43][44][45][46] . Besides, ALD is also a powerful method in thin film encapsulations for flexible electronics, due to the advantages of free pin-hole, excellent conformality and precise nanoscale thickness control on large area [47][48][49] . It is decent for surface defects passivation, dense thin film encapsulation, interstitial infilling and interface functional layers fabrication due to the characteristics of energy-dependent self-limiting reactions, dense uniform thin film fabrication, gas-phase infiltration and atomic level thickness control.…”

A review of highly reliable flexible encapsulation technologies towards rollable and foldable OLEDs

“…Using this approach, Han et al and Kwon et al tried to fabricate flexible multibarriers based on ALD-Al 2 O 3 [44,45]. 30-and 60-nm-thick ALD-Al 2 O 3 was deposited using trimethylaluminum (TMA) and H 2 O at 70°C.…”