Semimetallicity and Negative Differential Resistance from Hybrid Halide Perovskite Nanowires

In the rapidly progressing field of organometal halide perovskites, the dimensional reduction could open up new opportunities for device applications. Herein, taking the recently synthesized trimethylsulfonium lead triiodide (CH$_3$)$_3$SPbI$_3$ perovskite as a representative example, we carry out first-principles calculations and study the nanostructuring and device application of halide perovskite nanowires. We find that the one-dimensional (1D) (CH$_3$)$_3$SPbI$_3$ structure is structurally stable, and the electronic structures of higher-dimensional forms are robustly determined at the 1D level. Remarkably, due to the face-sharing [PbI$_6$] octahedral atomic structure, the organic ligand-removed 1D PbI$_3$ frameworks are also found to be stable. Moreover, the PbI$_3$ columns avoid the Peierls distortion and assume a semimetallic character, contradicting the conventional assumption of semiconducting metal-halogen inorganic frameworks. Adopting the bundled nanowire junctions consisting of (CH$_3$)$_3$SPbI$_3$ channels with sub-5 nm dimensions sandwiched between PbI$_3$ electrodes, we finally obtain high current densities and large room-temperature negative differential resistance (NDR). It will be emphasized that the NDR originates from the combination of the near-Ohmic character of (CH$_3$)$_3$SPbI$_3$-PbI$_3$ contacts and a novel NDR mechanism that involves the quantum-mechanical hybridization between channel and electrode states. Our work demonstrates the great potential of low-dimensional hybrid perovskites toward advanced electronic devices beyond actively-pursued photonic applications.