The effect of bending on the electrical and optical characteristics of aluminum-doped ZnO films deposited on flexible substrates

In this paper, electromechnical study is conducted on the performance of aluminum-doped zinc oxide film deposited on poly(ether sulfone) (PES) substrates using RF magnetron sputtering method. The change in electrical and optical properities due to face-out (FO) bending and face-in (FI) bending is investigated and a simple model method is proposed to understand the failure mechanisms. Static bending test and repeated bending test results show that the AZO films deposited on PES substrates can tolerate greater mechanical bending in the FO direction than that in the FI direction. When the value of strain is over 0.01, the resistivity increases significantly and cracks form. Accordingly, a 0.01 strain limit can be safely considered as a design parameter for projecting devices deposited on flexible substrates.