Controlling the growth of 2D conjugated coordination polymers to induce metallic and spin-dependent transport signatures

TL;DR

This study investigates the growth mechanisms of 2D conjugated coordination polymers, revealing how early-stage thin films exhibit superior electrical and spin-dependent properties, with implications for advanced electronic and spintronic devices.

Contribution

It uncovers the growth evolution of 2D cCPs in liquid-liquid synthesis, demonstrating how early-stage films achieve high conductivity and unique quantum transport signatures, challenging traditional growth paradigms.

Findings

Early-stage films are smoother and denser with higher conductivity (>3000 S/cm)

Quantum interference effects like weak antilocalisation are observed at low temperatures

Longer reaction times lead to less favorable electronic and spin properties

Abstract

Understanding growth evolution and thereby implementing precise microstructural tuning of two-dimensional (2D) conjugated coordination polymers (cCPs) is crucial to achieve efficient electronic conduction towards their full potential and to observe materials' intrinsic properties. However, fundamental understanding of how 2D cCPs films grow remains very limited. Here, we use copper-benzenehexathiol (Cu-BHT) cCP as a model system to unravel the growth evolution of layered films in liquid-liquid interfacial synthesis in order to identify strategies to achieve tuning of structure-property relationships. We find that thin films formed at the early stage of growth in 20 minutes facilitate smoother, denser, and horizontally oriented films, and thereby achieve higher electrical conductivity of > 3000 S/cm with a metallic temperature dependence down to 20 K. They also reveal signatures of quantum interference mediated weak antilocalisation and Kondo-like effect in magnetotransport at low temperatures. These phenomena are not observed when long reaction time was employed. Our findings offer a new perspective for the growth of dynamically reversible self-assemblies, that is different from the traditional paradigm of longer reaction time being associated with higher ordering and performance, and offer a platform to study spin-related transport properties of these materials with higher performance for advanced electronic, thermoelectric, and potential spintronic applications.