LAUSR

Charge neutral, non-conjugated organic radicals have emerged as extremely useful active materials for solid-state electronic applications due to their recently-demonstrated high electrical conductivity. This previous achievement confirmed the potential of radical-based macromolecules in organic electronic devices; however, charge transport in radical molecules has not been studied in great detail from a fundamental perspective. Here we demonstrate the charge transport in a non-conjugated organic small radical, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (h-TEMPO). The key chemical component of this radical molecule allows to form a single crystal organic radical via physical vapor deposition (PVD). While the charge transport of this macroscopic open-shell single crystal is a rather low, thermal annealing of the well-defined single crystal enables the molecule to have a rapid charge transfer reaction due to the electronic communication of open-shell sites with another, which results in electrical conductivities greater than 0.05 S m-1. The charge transfer occurs despite the fact that the radical organic molecules contain no conjugated segments and crystallinity. This effort demonstrates a drastically different model than the commonly accepted conjugated polymers or molecules for the creation of next-generation conductors.