Topological materials hold their unprecedented properties in the future electronic and spintronic devices. A very simple model to disclose topological electronics is the Su-Shrieffer-Heeger (SSH) model that can be observed in organic polyacetylene chains. The Zak phase can be defined as a (possibly the lowest order) topological number, $gamma$ - and then the Chern number and higher order Chern numbers for conventional topological insulators (TIs) and higher order TIs can be introduced. Collaroated with Prof. Fei Ma, Yan Li, and Hongwei Bao, we discovered that the famous 2D material blue and black phosphorene could form a 1D heterojunction, which exhibits a spontaneous charge density wave (CDW). It is also natural to have dimerization fault in forming CDW, and one could be able to observe the end state in such inorganic material, mimicking 1D SSH model. The "soliton" could also move under external perturbations, with a moderate moving barrier. This work is published in a recent PRB paper (Phys. Rev. B 2020, 102, 165308), see https://journals.aps.org/prb/abstract/10.1103/PhysRevB.102.165308.