Bi‐polaron Transport and Magnetic Field Induced Pauli Spin Blockade in Redox‐Active Molecular Junctions

We report the bi‐polaron transport and magnetic field induced Pauli spin‐blockade in solid‐state molecular junctions (MJs) evidenced by a positive magnetoresistance (MR). The junction was made of thin layers of redox‐active ruthenium polypyridyl‐oligomers Ru(tpy)2 sandwiched between conducting amorphous carbon (a‐C) electrodes. The redox‐active Ru(tpy)2 molecule, which enables small polaron and deep traps in the charge transport of the Ru(tpy)2 MJ as revealed by the temperature‐dependent current–voltage response, leads to the formation of the bi‐polaron and magnetic field induced Pauli spin blockade, resulting into the MR. At the meantime, the reliable and controllable device performance renders a rigid thickness‐dependent MR evolution. The bi‐polaron transport revealed in our study underscores the importance of the multi‐particle transport by molecular design in MJs and laid the foundation for magnetic‐electronic function in molecular‐scale devices. The bi‐polaron transport and magnetic field induced Pauli spin‐blockade were revealed in redox‐active molecules in molecular junctions (MJs), as evidenced by the magnetoresistance (MR) effect, which may bring new magnetic‐electronic functionality to molecular scale electronic devices.