Trion electroluminescence from semiconducting carbon nanotubes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Semiconducting single-walled carbon nanotubes (SWNTs) exhibit near-infrared emission primarily from exciton radiative relaxation.
• Doping SWNTs creates charged three-body excitons (trions), which emit light at lower energies than excitons.
• Weak trion photoluminescence is observable in doped SWNTs even at room temperature.

Purpose of the Study:

• To demonstrate and characterize strong trion electroluminescence in SWNT-based light-emitting transistors.
• To investigate the influence of different polymer-sorted SWNT species on trion emission.
• To explore the potential of trions as a tunable emission pathway in optoelectronic devices.

Main Methods:

• Fabrication of electrolyte-gated, light-emitting SWNT transistors using (6,5), (7,5), and (10,5) SWNT species.
• Electrochemical doping to induce high charge carrier densities in the transistor channel.
• Spectroscopic analysis of electroluminescence, comparing exciton and trion emission intensities and spectral positions.

Main Results:

• Demonstration of strong trion electroluminescence in SWNT transistors, with emission intensities comparable to or exceeding exciton emission.
• Observation of red-shifted trion emission attributed to high charge carrier densities.
• Tuning of the trion-to-exciton emission ratio via applied voltages.

Conclusions:

• Trion emission is a significant radiative pathway in doped SWNTs, particularly under high charge carrier densities achieved in transistor devices.
• The voltage-tunable trion emission enables the development of novel, narrow-linewidth, near-infrared light sources.
• These SWNT-based devices are solution-processable and operate efficiently at low voltages (<3 V).