Non-contact resistance measurement of transparent electrodes deposited on flexible display substrates under repetitive bending test by terahertz time domain spectroscopy

The objective of this study is to put forward a new non-contact resistance measurement method for repeating bending tests of transparent electrodes deposited on flexible display substrates. The study utilizes a terahertz time domain spectroscopy (THz-TDS) method to measure electrical properties of flexible polyethylene terephthalate/indium tin oxide samples up to 20,000 bending times. In addition, this study utilizes THz-TDS method to measure electrical characteristics of flexible substrates with hard-coat films. Accordingly, the percentage errors of measured sheet resistances based on THz-TDS method are less than or equal to 5.5% for comparison with a contact type four-point probe method or our previously reported flexible characteristic inspection system method. The values show a reasonable agreement with contact-mode sheet resistance measurements. Therefore, the electrical properties of thin films are measured offline or online easily by using this method.