Diameter-Dependent Band Gap Modification of Single-Walled Carbon Nanotubes by Encapsulated Fullerenes

Abstract

Band gap photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) encapsulating C 60 fullerenes (nanopeapods) is examined over a wide range of diameters (∼1.25-1.55 nm). The encapsulated fullerenes induce characteristic PL peak shifts that strongly depend on the tube diameter (d t ) and the "2n + m" family type {type I [mod(2n + m, 3) ) 1] and type II [mod(2n + m, 3) ) 2]}. This behavior can be explained by the strain-induced band gap shifts due to the C 60 insertion and the hybridization between the electronic states of SWCNTs and C 60 . The present results provide significant insights into band gap engineering of SWCNTs in future nanodevices.

Host–guest interaction between single‐wall carbon nanotubes and encapsulated C60 probed by resonance Raman spectroscopy

“…1, upper panels). On the basis of the previous Raman [7,8] and PL [4] studies, the observed peaks under the 1.33 eV excitation are assignable to 2n þ m ¼ 31 family (Fig. 1A, upper panel).…”

“…The C 60 NPDs and the empty SWCNTs were individually dispersed in the micelle D 2 O solutions to directly compare the photoluminescence (PL) results [4]. Briefly, NPDs or SWCNTs ($1 mg) were dispersed for 10 min in $20 mL of D 2 O containing 1 wt% of dodecylbenzene physica sulfonate (SDBS) using 500 W homogenizer (SONICS VCX500) equipped with titanium alloy tip (TI-6AL-4V).…”

“…The decomposed peaks (blue lines) were consistently assigned to each (n, m) tube based on the well-known 2n þ m family pattern that has frequently reported in the literature (see Ref. [4,5]). The RBM frequencies of each tube were obtained by averaging those observed under the several excitation wavelengths.…”

“…2 was got from standard deviation for average frequency of (n, m) tube. Based on the twodimensional (2D) PL contour map [4,5] and the 2D RBM phonon intensity map [8], each peak in the spectra can be assigned to (n, m) SWCNTs of 2n þ m ¼ 31, 34, and 37 family members. The frequencies of assigned tubes reasonably made an agreement with those in Refs.…”

Tuning the electrical transport properties of double-walled carbon nanotubes by semiconductor and semi-metal filling

“…6 Other studies have also suggested hybridization of the CNT's p states and filler element resulting in a slight change of the diameter. 8 It is important to understand the coupling between CNT's and the fillers to establish the specific change in the transport of this composite material. For example, encapsulation of an electron donor in metallic SWNT's enhances the electrical conductivity of the composite material 9 and titanium filling reduces the conductivity of SWNT's.…”