Topological Transition in One-Dimensional π-Conjugated Polymers via Strain Engineering

Area of Science:

• Condensed Matter Physics
• Materials Science
• Organic Chemistry

Background:

• Topological phases in low-dimensional organic polymers are achievable through synthesis.
• Controllable topological transitions are essential for practical device applications.
• Understanding strain-induced effects is key to harnessing topological properties.

Purpose of the Study:

• To propose a method for inducing topological transitions in 1D π-conjugated polymers via strain engineering.
• To investigate the role of orbital crossover in these topological transitions.
• To explore the potential for strain-dependent topological phase control.

Main Methods:

• Computational modeling of 10 one-dimensional (1D) π-conjugated polymers (CPs) in aromatic and quinonoid forms.
• Analysis of topological phases using the Zak invariant (Z2).
• Simulation of continuous external strain to induce orbital crossover and topological transitions.

Main Results:

• Quinonoid polymers exhibit nontrivial topological phases (Z2 = 1) with edge states.
• Aromatic polymers correspond to trivial topological phases (Z2 = 0).
• Poly(thiophene dioxide) (TDO) shows a reversible topological transition at 3.6% tensile strain due to HOMO-LUMO gap closure via orbital crossover.

Conclusions:

• Strain engineering provides a viable route to control topological transitions in 1D organic polymers.
• Orbital crossover is the mechanism driving strain-induced topological phase changes.
• This work establishes a foundation for designing organic materials with tunable topological properties for advanced applications.