Ion Enrichment-Mediated Charge Transfer in CNTs-Based Films for Infrared Electrochromism

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Carbon nanotubes (CNTs) are explored for flexible infrared electrochromic materials due to fast response.
• The precise mechanism linking infrared emissivity to bias voltage in CNTs is not well understood.

Purpose of the Study:

• To elucidate the microscopic mechanism of infrared emissivity modulation in CNT-based materials.
• To investigate the role of defect engineering in tuning electrochromic properties.

Main Methods:

• Fabrication of sulfur/nitrogen co-doped CNT (SNCNT) films as a model system.
• Investigation of ion enrichment-mediated charge transfer and its effect on conductivity.
• Utilizing first-principles calculations to correlate ion effects with electronic structure.

Main Results:

• Identified ion enrichment as the key process regulating conductivity and infrared emissivity.
• Revealed an asymmetric doping mechanism: anions induce hole doping, cations induce electron doping.
• Developed a multi-dimension model linking emissivity to resistance, charge dynamics, and structure.
• Achieved significant infrared modulation (Δε = 0.601) with memory effects in optimized SNCNT films.

Conclusions:

• Defect engineering in SNCNTs provides a pathway to understand and control infrared electrochromism.
• The ion-electron interaction within a capacitive framework governs the electrochromic response.
• SNCNT films show promise for advanced applications including infrared camouflage and information encryption.