  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. 
Quantum hybridization negative differential resistance from non-toxic   halide perovskite nanowire heterojunctions and its strain control