Direct coating of transparent and wear-resistant polysilsesquioxane on ultra-thin glass for flexible cover windows

This study presents a wear-resistant and anti-fragile ultra-thin glass (UTG) as a flexible cover window. Direct coating of ladder-like polysilsesquioxane (PSQ) onto UTG was introduced to achieve flexibility and protective properties at the same time. In contrast, conventional lamination-based protective films for UTG compromise surface hardness and wear resistance because of using the soft adhesive. The resulting cover window demonstrated pencil hardness of 8H and 1000 cycles of abrasion resistance with 91 % of optical transmittance. Pen and ball drop test results also revealed impact resistance of PSQ-coated UTG improved dramatically compared to the bare UTG. Lastly, a rigorous 200,000-fold test at 3R inward and 6R outward bending verifies the outstanding folding cycle reliability, making it suitable for innovative protective layers for the flexible display industry.