Orbital model unravelling slipped-stacking induced quantum interference in tetrahedral 2D conjugated polymers

Abstract

With the ongoing advancements in experimental techniques for two-dimensional conjugated polymers (2DCPs), significant reductions in disorder and the flourishing methods for structural manipulation have attracted increasing interest in their electronic structures. The tight-binding model taking molecular orbitals as the basis provides a conceptual framework for structural and functional design; however, further investigation is needed concerning the influence of secondary frontier orbitals and model construction in slipped-stacking multilayer structures. In this article, we concentrate on models for tetrahedral homopolymers, examining the role of secondary frontier orbitals through a recombined orbital basis. Results show that while a single-orbital model can give band structures that closely align with density functional theory calculations, including additional orbitals based on symmetry and phase considerations yields clearer chemical insights and facilitates straightforward extensions to multilayer systems. In particular, we emphasize a double-orbital model featuring a pair of linearly extended orbitals that cross at the center of the building block. Enhanced destructive quantum interference is observed in homopolymers compatible with this model when subjected to van der Waals interactions from an adjacent layer exhibiting a slipped stacking configuration. Through this crossed double-orbital model, the origins of the quantum interference can be effectively elucidated. Furthermore, we show that the doping-induced spin polarization in bilayers compatible with this model can be controlled by interlayer interference, a phenomenon for which our extended model provides an effective framework for analyzing.