Al₂O₃/TiO₂ Nanolaminate Thin Film Encapsulation for Organic Thin Film Transistors via Plasma-Enhanced Atomic Layer Deposition

TLDR

Organic electronic devices need passivation layers to shield sensitive active layers from moisture and oxygen, requiring films with excellent stability and mechanical properties, yet PEALD Al2O3 films, though good gas barriers, corrode significantly in water. The study examined how PEALD Al2O3 films deform in water and sought to create a corrosion‑resistant passivation layer using a PEALD‑based Al2O3/TiO2 nanolamination technique. This was achieved by fabricating Al2O3/TiO2 nanolaminate films via a PEALD process. The Al2O3/TiO2 nanolaminate films showed excellent water anticorrosion, low gas permeation, and could be processed below 100 °C, enabling organic thin‑film transistors that remained air‑stable for 52 days under 90 % RH at 38 °C.

Abstract

Organic electronic devices require a passivation layer that protects the active layers from moisture and oxygen because most organic materials are very sensitive to such gases. Passivation films for the encapsulation of organic electronic devices need excellent stability and mechanical properties. Although Al2O3 films obtained with plasma enhanced atomic layer deposition (PEALD) have been tested as passivation layers because of their excellent gas barrier properties, amorphous Al2O3 films are significantly corroded by water. In this study, we examined the deformation of PEALD Al2O3 films when immersed in water and attempted to fabricate a corrosion-resistant passivation film by using a PEALD-based Al2O3/TiO2 nanolamination (NL) technique. Our Al2O3/TiO2 NL films were found to exhibit excellent water anticorrosion and low gas permeation and require only low-temperature processing (<100 °C). Organic thin film transistors with excellent air-stability (52 days under high humidity (a relative humidity of 90% and a temperature of 38 °C)) were fabricated.