Macro- and atomic-scale observations of a one-dimensional heterojunction in a nickel and palladium nanowire complex

Abstract

The creation of low-dimensional heterostructures for intelligent devices is a challenging research topic; however, macro- and atomic-scale connections in one-dimensional (1D) electronic systems have not been achieved yet. Herein, we synthesize a heterostructure comprising a 1D Mott insulator [Ni(chxn)2Br]Br2 (1; chxn = 1R-2R-diaminocyclohexane) and a 1D Peierls or charge-density-wave insulator [Pd(chxn)2Br]Br2 (2) using stepwise electrochemical growth. It can be considered as the first example of electrochemical liquid-phase epitaxy applied to molecular-based heterostructures with a macroscopic scale. Moreover, atomic-resolution scanning tunneling microscopy images reveal a modulation of the electronic state in the heterojunction region with a length of five metal atoms (~ 2.5 nm), that is a direct evidence for the atomic-scale connection of 1 and 2. This is the first time that the heterojunction in the 1D chains has been shown and examined experimentally at macro- and atomic-scale. This study thus serves as proof of concept for heterojunctions in 1D electronic systems.

Hydrogen Bonding Propagated Phase Separation in Quasi-Epitaxial Single Crystals: A Pd–Br Molecular Insulator

“…Bright spots were observed on the Pd IV site in the MV–CDW domain and on the Pd III site in the AV–MH domain (Figure S6). Although the difference in the CDW Pd (IV−ρ) –Br···Pd (II+ρ) and MH Pd III –X–Pd III electronic states is small (ρ is almost 1), two domains with clear borders were observed at 113 K. On the other hand, the Ni–Pd heterojunction system has three domains, where the intermediate domain cannot be distinguished whether MV–CDW or AV–MH . These heterojunction interface differences may require attention in fabricating devices.…”

“…34 Although the difference in the CDW Pd (IV-ρ) -Br•••Pd (II+ρ) and MH Pd III -X-Pd III electronic states is small (ρ is almost 1), two domains were observed at 113 K due to the large difference in the Ni-Pd heterojunction. 40 However, the borderline is not parallel to the (1 1 0) plane, but is parallel to the (1 0 0) or (0 1 0) plane on the nanoscale, and is adjacent to the defects. At the same time, we observed quasi-epitaxial growth on the nanoscale between the CDW and MH states.…”

In situ synthesis of hierarchically-assembled three-dimensional ZnS nanostructures and 3D printed visualization

“…Transmission electron microscopy (TEM) is a typical tool to characterize near-atomic scale structures, capturing two-dimensional (2D) projected nanomaterials. The measuring technology helps the nanomaterials inspection to be more closely to atomic scales, hence the use of the technology would be a complementary strategy to fabricate advanced nanostructures 28 , 29 .…”

Orthogonal Grade-Separated Nanowiring of Molecular Single Chains

“…In general, Ni-type MX-Chains are in a Mott–Hubbard (MH) state in an M(III) averaged valence state because of a stronger electron correlation, whereas Pd- and Pt-type MX-Chains are in an M(II)/M(IV) mixed valent charge-density-wave (CDW) state due to strong Peierls instability . Optical, , magnetic, , and electrical properties − based on such 1D electronic systems, as well as ladder structures − and a 1D heterojunction, have been well studied so far. It should be noted that all reported MX-Chains adopt similar parallel arrangements.…”

“…Halogen-bridged metal complexes (MX-Chains, Figure 1a) are molecular single chains that are composed of alternating metal and halide ions. 10 21 Optical, 22,23 magnetic, 24,25 and electrical properties 26−29 based on such 1D electronic systems, as well as ladder structures 30−33 and a 1D heterojunction, 34 Fe(II) ions were aerobically oxidized to Fe(III) ions during the reaction and crystallization processes. The Fe(III) oxidation state was confirmed by Mossbauer spectroscopy (Figure S2).…”