Structural, Photophysical, and Transport Properties of Porous MAPbBr₃ Single Nanowire and Nanodevice for Electrochemical Sensing

In this paper, we report synthesis of porous methylammonium lead tribromide (MAPbBr₃) nanowires via self-template-directed method with dimensions of 13 ± 3 μm in length and 700 ± 100 nm in width. The perovskite single nanowires with correct compositions are demonstrated uniform in crystallinity and high in porosity by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The current-voltage (I-V) characteristics of a single nanowire display a linear behavior (Ohmic contact) from 300 K to 83 K with an average conductivity of 57.82 ± 4.8 S cm⁻¹, a hole concentration of 5.98 × 10¹⁸ cm⁻³, and hole mobility of 60.33 cm²V⁻¹S⁻¹ at 300 K. The single porous nanowire not only displays resistivity of approximately five orders of magnitude lower than those of previous reported values but is also stable and insensitive to the environment’s effects. Moreover, conductivity of porous nanowires can be modulated via the doping or substituting mechanisms when encountering heavy metal ions. The single nanowire device is applied as an electrochemical sensor in detecting four metal ions (Cu²⁺, Co²⁺, Hg²⁺, and Fe³⁺). The wide dynamic range in electrical conductivity of this porous single nanowire makes it a potential candidate for metal ion sensing with great sensitivity.