Durability under mechanical bending of the indium tin oxide films deposited on polymer substrate by thermionically enhanced sputtering

The emerging demand for flexible display panels has created a demand for coating techniques capable of depositing high-quality transparent conductive coatings (TCOs) on polymeric materials. This study demonstrates indium tin oxide (ITO) films deposited on polyethylene terephthalate (PET) substrates using a thermionic emission (TE) enhanced DC magnetron sputtering system to improve electrical and optical properties under static and dynamic mechanical bending.Experimental results show that the ITO-coated PET specimen prepared with TE and without TE presents an average transmittance in the visible region of the spectrum of 83% and 70%, and an electrical resistivity of 4.5 × 10−4 and 1.7 × 10−3 Ω cm, respectively. By contrast, the static bending test revealed that the critical radius of curvature (Rc) is 13.9 and 17.0 mm for the ITO-coated PET with and without TE. The dynamic bending test showed that the ITO-coated PET with TE is durable for more than 1200 cycles, while the corresponding number for the ITO-coated PET without TE is smaller than 50 cycles for the ITO-coated PET without TE. These results evidence that the ITO film deposited using the TE approach exhibits a higher degree of crystallinity and film adhesion than that deposited without TE. TE improves optical and electrical properties of the ITO coatings and their longer durability under mechanical bending.