  While low-dimensional organometal halide perovskites are expected to open up
new opportunities for a diverse range of device applications, like in their
bulk counterparts, the toxicity of Pb-based halide perovskite materials is a
significant concern that hinders their practical use. We recently predicted
that lead triiodide (PbI$_3$) columns de-rived from trimethylsulfonium (TMS)
lead triiodide (CH$_3$)$_3$SPbI$_3$ (TMSPbI$_3$) by stripping off TMS ligands
should be semimetallic, and additionally ultrahigh negative differential
resistance (NDR) can arise from the heterojunction composed of a TMSPbI$_3$
channel sandwiched by PbI$_3$ electrodes. Herein, we computationally explore
whether similar material and device characteristics can be obtained from other
one-dimensional halide perovskites based on non-Pb metal elements, and in doing
so deepen the understanding of their mechanistic origins. First, scanning
through several candidate metal halide inorganic frameworks as well as their
parental form halide perovskites, we find that the germanium triiodide
(GeI$_3$) column also assumes a semimetallic character by avoiding the Peierls
distortion. Next, adopting the bundled nanowire GeI$_3$-TMSGeI$_3$-GeI$_3$
junction configuration, we obtain a drastically high peak current density and
ultrahigh NDR at room temperature. Furthermore, the robustness and
controllability of NDR signals under strain are revealed, establishing its
potential for flexible electronics applications. It will be emphasized that,
despite the performance metrics notably enhanced over those from the
PbI$_3$-TMSPbI$_3$-PbI$_3$ case, these device characteristics still arise from
the identical quantum hybridization NDR mechanism.
