Local charge trapping in conjugated polymers resolved by scanning Kelvin probe microscopy

Area of Science:

• Materials Science
• Polymer Science
• Condensed Matter Physics

Background:

• Conjugated polymers exhibit heterogeneous microstructures.
• Understanding nanoscale electronic properties is crucial for material applications.
• The impact of microstructure on charge transport remains unclear.

Purpose of the Study:

• To investigate nanoscale charge transport in semicrystalline conjugated polymers.
• To elucidate the role of microstructure, specifically grain boundaries, in charge trapping.
• To correlate microstructure with electronic properties on a 100 nm scale.

Main Methods:

• Utilized scanning Kelvin probe microscopy (SKPM).
• Employed resolution-enhancing carbon nanotube tips for nanoscale imaging.
• Studied charge transport in a chain-extended, semicrystalline conjugated polymer.

Main Results:

• Identified disordered grain boundaries as preferential charge trapping sites.
• Observed nanoscale variations (100 nm) in carrier concentration under accumulation.
• Demonstrated the direct link between microstructure and charge distribution.

Conclusions:

• Nanoscale heterogeneity significantly influences charge transport in conjugated polymers.
• Grain boundaries act as critical defects affecting electronic performance.
• SKPM with nanotube tips provides valuable insights into nanoscale electronic phenomena.