Relation between structure and electronic properties of amorphous MEH-PPV polymers

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Amorphous polymeric semiconductors are crucial for organic electronics.
• Understanding charge transport in these materials is key to device performance.
• Existing models often simplify the complex electronic structure.

Purpose of the Study:

• To build large-scale models of MEH-PPV using molecular dynamics.
• To quantitatively assess electronic structure and charge transport properties.
• To identify key factors influencing charge mobility in amorphous polymers.

Main Methods:

• Classical molecular dynamics simulations for model construction.
• Electronic structure calculations using a balanced set of approximations.
• Analysis of conformational and electrostatic disorder effects.

Main Results:

• Electronic structure is primarily dictated by chain conformational disorder.
• Electrostatic disorder and interchain coupling have minimal impact.
• Orbital localization length is energy-dependent, not constant.
• A moderate correlation exists between chain planarity and orbital localization.

Conclusions:

• Conformational disorder is the dominant factor in MEH-PPV's electronic properties.
• Current variable range hopping models may need refinement for amorphous systems.
• Future transport models should account for energy-dependent localization and static disorder.