Effect of Inorganic Buffer Layers on the Photoelectric Properties and Bending Resistance Performance of Flexible AZO Films

Aluminum doped Zinc Oxide (AZO) thin films with TiO₂, SnO₂ and ZnO buffer layers were deposited on the flexible PET substrates by intermediate frequency reaction magnetron sputtering method at room temperature. The effects of different buffer layers on the photoelectric properties and bending resistance performance of flexible AZO films were investigated. The results showed that three kinds of buffer layers improved the electrical properties of the flexible AZO thin films. The AZO thin film with SnO₂ buffer layer deposited Ar/O₂ ratio of 5∶1 showed the best performance, of which the reducing rate in the resistivity reached 90% and the average optical transmittance was over 85% in the visible range. The changes in the electrical resistance of the flexible AZO thin films under cyclic bending condition were studied as well. The AZO thin film with SnO₂ or ZnO buffer layer exhibited an excellent electrical stability after inward repeated bending cycles, at steps of 100, to a maximum number of 1 000, with radius fixed at 1.2 cm. The relative resistivity increment was always below 10%, whereas the dramatic increase of the electrical resistance is more than a factor of 250 after 800 cycles of bending for the as-grown ones. The TiO₂ and SnO₂ buffer layers were found to be better when the AZO films are outward bent at the same cycles, and their relative resistivity increments were maintained at about 6% and 12%, respectively.