Sub-4 nm mapping of donor-acceptor organic semiconductor nanoparticle composition

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Organic semiconductor blends are crucial for organic electronics, but their nanoscale morphology is challenging to characterize.
• Understanding the precise distribution of donor and acceptor materials within nanoparticles is key to optimizing device performance.

Purpose of the Study:

• To develop and demonstrate a sub-4 nm compositional mapping technique for donor:acceptor nanoparticles.
• To analyze the internal morphology of eco-friendly colloidal dispersions for organic electronics.

Main Methods:

• Low-energy scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectroscopy (EDX) for elemental mapping.
• Utilizing unique fingerprint elements (e.g., Si, S, N) to differentiate donor and acceptor materials.
• Employing synchrotron-based scanning transmission X-ray microscopy (STXM) as a complementary superior chemical contrast technique for specific blends.

Main Results:

• Achieved sub-4 nm compositional mapping of donor:acceptor nanoparticles, revealing internal morphology.
• Demonstrated qualitative and quantitative compositional mapping with STEM EDX, resolving sub-domains in nanoparticles as small as 30 nm.
• Identified STXM as superior for blends lacking unique elements or with sensitive fingerprint elements.

Conclusions:

• The developed sub-4 nm mapping technology is highly promising for optimizing organic semiconductor blends.
• This technique has significant potential for applications in organic electronics, including solar cells and bioelectronics, as well as in photocatalysis and nanomedicine.