Carrier density and delocalization signatures in doped carbon nanotubes from quantitative magnetic resonance

• Published in: Nanoscale horizons 2024-01, Vol.9 (2), p.278-284
• Main Authors: Hermosilla-Palacios, M. Alejandra, Martinez, Marissa, Doud, Evan A, Hertel, Tobias, Spokoyny, Alexander M, Cambré, Sofie, Wenseleers, Wim, Kim, Yong-Hyun, Ferguson, Andrew J, Blackburn, Jeffrey L
• Format: Article
• Language: English
• Subjects: carbon nanotubes; Carrier density; Carrier mobility; Charge transfer; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Current carriers; Doping; Hole mobility; NANOSCIENCE AND NANOTECHNOLOGY; NMR; Nuclear magnetic resonance; Optoelectronic devices; Organic semiconductors; organics; Semiconductor materials; Single wall carbon nanotubes
• ISSN: 2055-6756; 2055-6764; 2055-6764
• DOI: 10.1039/d3nh00480e

High-performance semiconductor materials and devices are needed to supply the growing energy and computing demand. Organic semiconductors (OSCs) are attractive options for opto-electronic devices, due to their low cost, extensive tunability, easy fabrication, and flexibility. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have been extensively studied due to their high carrier mobility, stability and opto-electronic tunability. Although molecular charge transfer doping affords widely tunable carrier density and conductivity in s-SWCNTs (and OSCs in general), a pervasive challenge for such systems is reliable measurement of charge carrier density and mobility. In this work we demonstrate a direct quantification of charge carrier density, and by extension carrier mobility, in chemically doped s-SWCNTs by a nuclear magnetic resonance approach. The experimental results are verified by a phase-space filling doping model, and we suggest this approach should be broadly applicable for OSCs. Our results show that hole mobility in doped s-SWCNT networks increases with increasing charge carrier density, a finding that is contrary to that expected for mobility limited by ionized impurity scattering. We discuss the implications of this important finding for additional tunability and applicability of s-SWCNT and OSC devices. Molecular charge transfer doping affords widely tunable carrier density and conductivity in s-SWCNTs (and OSCs in general), however, a pervasive challenge for such systems is reliable measurement of charge carrier density and mobility.