Enhancing Repetitive Uniaxial Mechanical Bending Endurance at R=2mm Using an Organic Trench Structure in Foldable Low Temperature Poly-Si Thin-Film Transistors

At bending radius smaller than 2mm, flexible low temperature polycrystalline silicon thin film transistors (LTPS TFTs) suffer from strong uniaxial mechanical stress and demonstrate severe degradation of electrical characteristics. Our previous study showed repetitive mechanical uniaxial bending damages the gate insulator, causing carriers to trap into it. Here, degradation after channel width-axis direction bending was found to be more pronounced than after channel length-axis bending. In order to alleviate this degradation, an organic structure flexible LTPS TFT was proposed to enhance mechanical stress endurance. After 100,000 iterations of uniaxial mechanical bending at R=2mm, degradation nearly disappeared in devices with this organic trench structure.