3D Printing of Conductive Polymer via Photo‐Oxidation Polymerization inside Metal‐Organic Framework

Abstract Despite the crucial role of conductive polymers in flexible microelectronics, current 3D fabrication of conductive polymers is plagued by solubility problems and low precision. Femtosecond laser direct writing (FsLDW) offers a potential solution, yet complex 3D structures constructing of conductive polymers remains challenging. Here, an innovative approach that utilizes inorganic microporous metal‐organic framework (MOF) crystals as supporting substrates for 3D printing of polypyrrole (PPy) is developed. Upon photoexcitation, a novel photosensitizer 2‐chlorophenothiazine (2‐Cl‐PTh) triggers the generation of singlet oxygen, enabling the polymerization of pyrrole (Py) monomer. Multilayer patterns and complex 3D structures of PPy are achieved within the MOF matrix by FsLDW. The resulting hybrid micro‐nanostructures leverage the MOF's inherent structural support, effectively imparting electrical conductivity to the otherwise insulating MOF material. Moreover, photosensitizer fluorescence allows in situ characterization, guiding the design of functional 3D conductive polymers. This technique provides a new route to fabricate conductive polymer structures with high spatial resolution and tailored morphologies, opening a pathway for 3D printing of electrically active composites as well as advanced microelectronic devices.