Improvement of mechanical reliability by patterned silver/Indium-Tin-Oxide structure for flexible electronic devices

We report the effect of silver (Ag)-buffer layer Indium-Tin-Oxide (ITO) film on a polyethylene terephthalate substrate on the electrical, optical and reliable properties for transparent-flexible displays. The electrical and optical characteristics of an ITO-only film and an Ag-layer-inserted ITO film are measured and compared to assess the applicability of the triple layered structure in flexible displays. The sheet resistance, the resistivity and the light transmittance of the ITO-only film were 400 Ω/sq, 1.33 × 10^{- 3} Ω-cm and 99.2%, while those of the ITO film inserted with a 10 nm thick Ag layer were 165 Ω/sq, 4.78 × 10^{- 4} Ω-cm and about 97%, respectively. To evaluate the mechanical reliability of the different ITO films, bending tests were carried out. After the dynamic bending test of 900 cycles, the sheet resistance of the ITO film inserted with the Ag layer changed from 154 Ω/sq to 475 Ω/sq, about a 3-time increase but that of the ITO-only film changed from 400 Ω/sq to 61,986 Ω/sq, about 150-time increase. When the radius is changed from 25 mm to 20 mm in the static bending test, the sheet resistance of the ITO-only film changed from 400 to 678.3 linearly whereas that of the Ag-layer inserted ITO film changed a little from 154.4 to 154.9. These results show that Ag-layer inserted ITO film had better mechanical characteristics than the ITO-only film.