Theoretical Approaches toward Designing Organic Molecule Infilling for n- and p-Type Single-Walled Carbon Nanotubes

Organic molecules (OMs) infilled into single-walled carbon nanotubes (SWCNTs) have been shown to facilitate carrier injection, enabling the construction of ultralow-power CNT-based electronic devices. However, systematic investigations into the fundamental physical mechanism of carrier injection and the regulation of charge transfer by OMs remain lacking. Therefore, we systematically explore the interaction mechanism and charge transfer regulation between OMs and SWCNTs through first-principles calculations. Our results reveal that carrier injection in SWCNTs is primarily governed by the relative alignment of the OMs’ ionization energy (IE) and electron affinity (EA) with respect to the Fermi level of the SWCNTs, thereby enabling stable carrier injection. Furthermore, for n-type SWCNTs, functional group engineering offers an effective means to tune the ionization energy of OMs, thus modulating charge transfer in the composite structures. Notably, we establish a strong linear correlation between the transferred charge and the energy difference between the ionization energy and the SWCNT Fermi level.