Rapid fabrication of Al2O3 encapsulations for organic electronic devices

Abstract

Organic electronics have earned great reputation in electronic industry yet they suffer technical challenges such as short lifetimes and low reliability because of their susceptibility to water vapor and oxygen which causes their fast degradation. This paper report on the rapid fabrication of Al2O3 encapsulations through a unique roll-to-roll atmospheric atomic layer deposition technology (R2R-AALD) for the life time enhancement of organic poly (4-vinylphenol) (PVP) memristor devices. The devices were then categorized into two sets. One was processed with R2R-AALD Al2O3 encapsulations at 50°C and the other one was kept as un-encapsulated. The field-emission scanning electron microscopy (FESEM) results revealed that pin holes and other irregularities in PVP films with average arithmetic roughness (Ra) of 9.66nm have been effectively covered by Al2O3 encapsulation having Ra of 0.92nm. The X-ray photoelectron spectroscopy XPS spectrum for PVP film showed peaks of C 1s and O 1s at the binding energies of 285eV and 531eV, respectively. The respective appearance of Al 2p, Al 2s, and O 1s peaks at the binding energies of 74eV, 119eV, and 531eV, confirms the fabrication of Al2O3 films. Electrical current–voltage (I–V) measurements confirmed that the Al2O3 encapsulation has a huge influence on the performance, robustness and life time of memristor devices. The Al2O3 encapsulated memristor performed with superior stability for four weeks whereas the un-encapsulated devices could only last for one week. The performance of encapsulated device had been promising after being subjected to bending test for 100 cycles and the variations in its stability were of minor concern confirming the mechanical robustness and flexibility of the devices.