66‐2: Highly Transparent, Colorless Optical Film with Outstanding Mechanical Strength and Folding Reliability Using Mismatched Charge‐Transfer Complex Intensification

This study describes a novel colorless polyimide window film using the concept of charge‐transfer complex (CTC) intensification. The resulting film has a tensile modulus of 8.4 GPa, total transmittance of ≈90%, and yellow index below 3. This is the best‐recorded balance between mechanical strength and optical properties for a highly flexible optical film. Additionally, the film exhibits a pencil hardness grade over 2H and folding reliability over 200,000 folding/unfolding cycles. These outstanding properties are attributed to the unique supramolecular structure, which features multiple hydrogen bonding and salt complexation interactions that lead to CTC intensification.