Innovative stress-release method for low-stress flexible Al2O3 encapsulation films in OLED applications

This study presents a low residual tensile stress, flexible thin film encapsulation with a 2 mm bending radius based on atomic layer deposition (ALD), specifically plasma-enhanced ALD (PEALD). By utilizing polydimethylsiloxane (PDMS) to release stress during deposition, we achieved a wrinkled morphology film that reduces stress magnitude from 103 to 102 compared to conventional Al2O3 films. This wrinkled film enhances optical modulation to light extraction, increasing the external quantum efficiency (EQE) of organic light-emitting diode (OLED) by up to 14.95%. The water vapor transmission rate (WVTR) is 4.49 × 10−5 g/m2/day at 60 °C/90% RH, and the film retains about 90% of its initial properties after 10,000 bending cycles. This work introduces a novel solution for flexible ALD encapsulation, demonstrating ultra-flexible properties while improving device efficiency.