Stable organic molecules with a closed-shell structure are inherently insulators. Conventionally, generating charge carriers required "mixing (doping)" multiple molecules to facilitate charge transfer. In contrast, by employing a molecular design that introduces proton faults alongside the delocalization of π-orbitals, open-shell molecules with an unpaired electron (zwitterionic radicals) can acquire chemically stable carriers without doping. This unique molecular design guideline has enabled the versatile creation of materials ranging from chemically stable organic semiconductors to organic metals.

The developed molecule, "tetrathiafulvalene-extended dicarboxylate (TED)," is the first single-component organic molecule to exhibit metallic conductivity under ambient pressure. The in-plane electrical conductivity of its layered single crystal exceeds 2300 S/cm at room temperature, ranking among the highest for organic materials. Moreover, it maintains this high conductivity even after several months of exposure to air, making it highly promising for various applications, including transparent electrodes. For the industrial application of these functional organic electronic materials, conventional patterning methods such as lithography are not always optimal. Therefore, we developed a next-generation fine-wiring technology that is fully compatible with biological and organic devices, eliminating the need for high-boiling-point solvents or thermal processing during the wiring process.