Design and Fabrication of PDMS/Al2O3 Hybrid Flexible Thin Films for OLED Encapsulation Applications

Highly effective flexible thin film encapsulation (TFE) is significant and challenging for organic light-emitting diodes (OLEDs). In this work, the Al2O3 film fabricated by the atomic layer infiltration (ALI) technique penetrates into the PDMS material to form PDMS/Al2O3 hybrid flexible thin films for OLED encapsulation to prolong its lifetime. It was found that the penetrative depth and density of Al2O3 in PDMS could be regulated by the pulse time of the ALI precursor and reached saturation. The penetration of the Al2O3 film could not only enhance the barrier performance of PDMS/Al2O3 hybrid films but also alleviate the interfacial stress between PDMS and Al2O3. As a result, 3 pairs of PDMS/Al2O3 hybrid films with a water vapor transmission rate (WVTR) of 9.24 × 10–5 g/m2/day measured at 25 °C/50% RH were successfully prepared. The hybrid films were applied as encapsulation layers for OLED devices, whose brightness remains more than 50% of the initial brightness, exhibiting great barrier properties. Finally, the relationships between the penetrative degree, inorganic layer thickness, and maximum stress of PDMS/Al2O3 hybrid flexible films under different bending deformations were simulated and verified by the experiment. These results indicate the promising application of PDMS/Al2O3 hybrid films prepared by ALI in OLED encapsulation and stretchable, wearable, and flexible devices.