Electrically Tailored Metachrosis in ZnO-C Nanowires.

Carbon incorporated zinc oxide (ZnO:C) nanowires (NWs) are found to be remarkable morphing NWs. We show that the physical properties of ZnO:C NWs are engineered via the passage of electric current to produce fluorescence differences and negative differential resistance as well as electroluminescence. When a ZnO:C NW is subjected to an applied voltage bias and under ultraviolet (UV) excitation, electron-hole separation due to the voltage biasing suppresses their fluorescence at low voltages. At medium voltages, the NW exhibits metastable chemical changes that translates to tunable and reversible optical alterations akin to metachrosis found in chameleons. Concurrently, the NW displays electrical alterations with negative differential resistance behaviors. At higher voltages, these NWs are permanently modified with distinct heterogeneous chemical stoichiometry, fluorescence, and electronic properties. Such heterogeneity within the NW allows for emergence of junctions capable of electroluminescence.