High Yield Organic Superconductors via Solution-Phase Alkali Metal Doping at Room Temperature

Alkali metal doping is an essential process for developing organic superconductors. The conventional vapor-phase alkali metal doping, however, frequently suffers from low efficiency and poor reproducibility mainly due to the inhomogeneous reaction between alkali metal vapor and target organic molecule powder. To overcome this issue, here we developed a facile and highly reproducible solution-phase alkali metal doping (SPD) and successfully applied it to prepare potassium-doped fullerene (K₃C₆₀) superconductors. Different from the conventional vapor-phase alkali metal doping, the SPD method resulted in almost perfect diamagnetism with an unprecedented high shielding fraction (∼99.5%) with high reproducibility (>80%). It works well with popular commercially available solvents, like ammonia solution in THF, methylamine solution in THF, and even pure THF at room temperature. We believe that our highly facile and efficient SPD approach will be a great help for the finding of next-generation organic superconductors, especially searching for high-T_c organic superconductors.