Preparation and Bending Properties of Cu/ITO/PET Flexible Films

Cu/ITO/PET flexible films were fabricated using magnetron sputtering, and a mechanical testing device was set up to conduct bending and cyclic bending experiments on the films. The sheet resistance variations of the films under different bending conditions were measured by a four-probe tester, and the surface morphologies of the films before and after bending were observed via scanning electron microscopy （SEM）. The experimental results reveal the following: During the bending process, as the bending radius decreases to 7 mm, the sheet resistance of the film changed significantly under the inner bending mode. When the bending radius is further reduced to 3 mm, more obvious cracks form on the film surface under the outer bending mode compared with the inner bending mode, resulting in a larger sheet resistance. At a bending radius of 9 mm, after 1 500 cycles of cyclic bending, subtle cracks appear in the film under the inner bending mode, while no cracks are observed under the outer bending mode. Notably, the sheet resistance under the inner bending mode is larger than that under the outer bending mode. When the inner and outer bending radii decrease from 9 mm to 3 mm, the relative variation rate of the sheet resistance remains within 8%. When both the inner and outer bending radii are fixed at 9 mm, after six groups of bending experiments, the relative variation rate of the sheet resistance is within 6% for all groups. Overall, the prepared flexible films exhibit excellent electrical conductivity and bending resistance, demonstrating their potential applications in flexible electronic devices requiring mechanical flexibility and stable electrical performance. The comprehensive analysis of sheet resistance variations and surface morphologies under different bending conditions provides a theoretical basis for the design and optimization of flexible conductive films in practical engineering applications.