Quadrites and crossed-chain crystal structures in polymer semiconductors

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Crystallography

Background:

• High-performance conjugated polymers are crucial for organic photovoltaics (OPVs) and transistors.
• Typical polymer crystallization leads to parallel chain alignment, causing anisotropic charge transport.
• This anisotropy limits device efficiency and performance.

Purpose of the Study:

• To investigate an unusual intercrystallite relationship in conjugated polymers.
• To explore how this relationship impacts nanoscale charge transport properties.
• To understand the potential for improved charge transport pathways.

Main Methods:

• Utilized advanced microscopy techniques to observe polymer crystallization at the nanoscale.
• Analyzed the crystallite orientation and intercrystallite interfaces.
• Investigated the charge transport properties in relation to the observed structures.

Main Results:

• Demonstrated a novel epitaxial relationship between thin lamellae with crossed-chains at the interface.
• Observed that these crossed-chain structures facilitate efficient quasi-three-dimensional (3D) charge transport.
• Found that this arrangement acts as an 'electronic shunt', mitigating the negative impact of grain boundaries and defects.

Conclusions:

• The identified crossed-chain intercrystallite relationship offers a new paradigm for designing high-performance organic electronic materials.
• This structural motif enhances charge transport by creating quasi-3D pathways, overcoming limitations of anisotropic transport.
• The findings suggest a route to reduce the detrimental effects of grain boundaries and defects in polymer-based devices.