Band gap engineering in polymers through chemical doping and applied mechanical strain

Area of Science:

• Computational materials science
• Polymer physics
• Condensed matter theory

Background:

• Crystalline polymers like polyethylene, polypropylene, and polystyrene are crucial for dielectric applications.
• Understanding and engineering their electronic band gaps is key to improving performance.
• Current experimental data for band gaps can be limited or challenging to obtain.

Purpose of the Study:

• To computationally investigate the electronic band gaps of common crystalline polymers.
• To explore methods for tuning these band gaps, including chemical doping and mechanical strain.
• To assess the potential for these engineered polymers in advanced dielectric materials.

Main Methods:

• Density functional theory (DFT) simulations.
• Many-body perturbation theory (MBPT) calculations.
• Exploration of chemical modifications and mechanical stress effects.

Main Results:

• Accurate prediction of band gaps for polyethylene (8.6 eV single-chain, 9.1 eV bulk).
• Demonstrated significant tunability of band gaps via doping and strain (several eV range).
• Showcased that mechanical strain can alter band gaps without affecting dielectric constant.

Conclusions:

• Computational methods accurately predict polymer band gaps.
• Chemical doping and mechanical strain offer viable routes to engineer polymer electronic properties.
• These findings have significant implications for developing next-generation polymeric dielectric materials for energy storage.