Highly transparent and flexible TiN doped In₂O₃ (ITON)/Ag-Ti/ITON multilayer electrodes coated on polyethylene terephthalate substrate

We investigated characteristics of TiN doped In₂O₃ (ITON)/Ag-Ti/ITON multilayer films prepared by using co-sputtering and thermal evaporation at room temperature to use as transparent and flexible electrodes. The optimized ITON(40 nm)/Ag-Ti(14 nm)/ITON(40 nm) multilayer film showed a sheet resistance of 4.136 Ohm/square and an average transmittance of 86.45% at visible range between 400 and 800 nm. In addition, the ITON/Ag-Ti/ITON multilayer film exhibited a constant resistance change (R/R₀) below critical outer bending radius of 6 mm, which is smaller than typical Sn-doped In₂O₃ films. At dynamic fatigue tests, the ITON/Ag-Ti/ITON film showed a constant resistance change during 10,000 times repeated outer/inner bending cycles due to outstanding flexibility of the Ag-Ti interlayer and amorphous structure of the ITON layer. Low sheet resistance, high optical transmittance, and outstanding mechanical properties of ITON/Ag-Ti/ITON multilayer films indicate that ITON-based hybrid electrode is promising flexible and transparent electrodes for high performance flexible photovoltaics.