Aligned Carbon Nanotube Thin Films from Liquid Crystal Polyelectrolyte Inks.

Area of Science:

• Materials Science
• Nanotechnology
• Energy Conversion

Background:

• Single-walled carbon nanotubes (SWCNTs) are promising for electronic applications.
• Fabrication methods often induce damage, affecting performance.
• Achieving highly aligned SWCNT films is crucial for efficient charge transport.

Purpose of the Study:

• To develop a novel fabrication method for SWCNT thin films.
• To improve the electrical and optical properties of SWCNT films.
• To enhance the performance of SWCNT-based solar cells.

Main Methods:

• Fabrication of SWCNT thin films using solution shearing of high-concentration polyelectrolyte inks.
• Preparation of inks via stirring SWCNTs with sodium in dimethylacetamide, avoiding sonication.
• Characterization of film alignment using polarized absorption measurements and surface roughness via atomic force microscopy.

Main Results:

• Achieved well-aligned SWCNT films with a 2D nematic order parameter of ~0.7.
• Films exhibited a high DC electrical to optical conductivity ratio (σ(DC)/σ(OP)) of ~35 after p-doping, corresponding to >7000 S cm⁻¹.
• SWCNT-silicon solar cells using these films showed an order of magnitude greater power conversion efficiency compared to vacuum-filtered films.

Conclusions:

• Solution shearing of polyelectrolyte inks is an effective, damage-free method for fabricating highly aligned SWCNT films.
• The enhanced alignment and conductivity of these films significantly boost solar cell performance.
• This approach offers a pathway to high-performance carbon nanotube-based electronic devices.