Conductance Switch of a Bromoplumbate Bistable Semiconductor by Electron-Transfer Thermochromism

Electron-transfer (redox) thermochromism was successfully used for switching the conductance of semiconductors, by introducing a thermally active organic component into an inorganic semiconducting framework. A moisture-resistant semiconductor {(MV)₂ [Pb₇ Br₁₈ ]}_n (MV²⁺ =methyl viologen cation) has been prepared through an in situ synthetic method for MV²⁺ . It features a rare 3D haloplumbate open framework and unprecedented electron-transfer thermochromic behavior in haloplumbates. The electrical conductivity of this compound dropped significantly after coloration and restored after decoloration, which was satisfactorily explained by valence band XPS and theoretical data. This work not only offers a new approach to modify electrical properties of semiconductors without altering components or structures, but may lead to the development of over-temperature color indicators, circuit overload protectors or photovoltaic materials.