Localized Black Polyimide Absorbers for Low-Reflectance Ag Metal Mesh Electrodes

Flexible transparent conducting electrodes based on metal mesh structures can achieve low sheet resistance but often exhibit visible reflection from the metallic lines. Here, we introduce a localized black polyimide (BPI) light absorption layer near the Ag mesh lines to reduce metal-induced reflection while preserving the essential electrode characteristics. The BPI layer, consisting of carbon-black-dispersed polyimide, was patterned by combining thermal imprinting with Ag nanoparticle ink filling, thermal treatment, and selective etching, thereby localizing the light-absorption layer near the Ag mesh lines. At 550 nm, the localized BPI layer reduced the reflectance of the Ag electrode region from 50.22% to 4.94%, corresponding to a 90.16% reduction. Because the BPI layer was selectively self-positioned at the reflective metal-line region, this local reduction in reflectance provides a structural route to reducing the visibility of metal mesh electrodes. The fabricated electrode maintained transparent-electrode characteristics, with only a limited change in sheet resistance after selective etching and repeated bending.