Anisotropic Photoluminescence of Poly(3-hexyl thiophene) and Their Composites with Single-Walled Carbon Nanotubes Highly Separated in Metallic and Semiconducting Tubes

Abstract

In this work, the effect of the single-walled carbon nanotubes (SWNTs) as the mixtures of metallic and semiconducting tubes (M + S-SWNTs) as well as highly separated semiconducting (S-SWNTs) and metallic (M-SWNTs) tubes on the photoluminescence (PL) of poly(3-hexyl thiophene) (P3HT) was reported. Two methods were used to prepare such composites, that is, the chemical interaction of the two constituents and the electrochemical polymerization of the 3-hexyl thiophene onto the rough Au supports modified with carbon nanotubes (CNTs). The measurements of the anisotropic PL of these composites have highlighted a significant diminution of the angle of the binding of the P3HT films electrochemical synthetized onto Au electrodes covered with M + S-SWNTs. This change was attributed to metallic tubes, as was demonstrated using the anisotropic PL measurements carried out on the P3HT/M-SWNTs and P3HT/S-SWNTs composites. Small variations in the angle of the binding were reported in the case of the composites prepared by chemical interaction of the two constituents. The proposed mechanism to explain this behavior took into account the functionalization process of CNTs with P3HT. The experimental arguments of the functionalization process of CNTs with P3HT were shown by the UV-VIS-NIR and FTIR spectroscopy as well as surface-enhanced Raman scattering (SERS). A PL quenching process of P3HT induced both in the presence of S-SWNTs and M-SWNTs was reported, too. This process origins in the various de-excitation pathways which can be developed considering the energy levels diagram of the two constituents of each studied composite.

Polymethyl(1–Butyric acidyl)silane–Assisted Dispersion and Density Gradient Ultracentrifugation Separation of Single–Walled Carbon Nanotubes

“…In the 458 nm excitation spectra (Figure 8a), the RBM peaks originating from the SWNTs in the bottom brown layer are assigned to semiconducting (13,9), (14,6), (17,0), and (13,5) tubes (Figure S14a), and those from the SWNTs in the top green layer to semiconducting (16,6), (14,6) On the other hand, according to the electronic energy band theory, the fine features observed in the optical absorption spectra of SWNTs are applicable to the assignment of their (n, m) chiral indices [57]. As shown in Figure S13 and Table S2, metallic (9,9), (15,3), (14,5), (13,7), (18,0) and (15,6) species as well as semiconducting (12,4), (11,6), (10,8), (14,3), (13,5), (17,0), (14,6), (16,5) and (16,6) ones are assigned for the SWNTs dispersed in the aqueous solution of BA-PMS. It is obvious that all of the chiral indices assigned in line with the principal fitted RBM peaks in Figure 7 are agreement quite well with the results of the fine optical features.…”

“…In the 633 nm excitation spectrum (Figure 7b), the peaks in the range of 110-166 cm −1 are attributed to sc-SWNTs, while the peaks in the range of 166-224 cm −1 to m-SWNTs. The RBM peaks at 149 and 166 cm −1 are identified as semiconducting (15,10) and (16,6) SWNTs with diameters of 1.71 nm and 1.54 nm, respectively, whereas the RBM peaks at 177, 191, and 210 cm −1 are identified as metallic (15,3), (14,5), and (14,2) SWNTs with diameters of 1.34, 1.31, and 1.18 nm, respectively. On the other hand, according to the electronic energy band theory, the fine features observed in the optical absorption spectra of SWNTs are applicable to the assignment of their (n, m) chiral indices [57].…”

“…To identify the chiral indices of SWNTs after DGU separation, resonant Raman scattering spectra were also collected for the SWNTs both in the top green layer and in the bottom brown layer at the excitations of 458, 514, 532, and 633 nm, respectively. In the 458 nm excitation spectra (Figure 8a), the RBM peaks originating from the SWNTs in the bottom brown layer are assigned to semiconducting (13,9), (14,6), (17,0), and (13,5) tubes (Figure S14a), and those from the SWNTs in the top green layer to semiconducting (16,6), (14,6) and (13,5) tubes along with a metallic (13,13) one (Figure S15a). In the 633-nanometer excitation spectra (Figure 8b), the RBM peaks originated from the SWNTs in the top green layer are assigned to metallic (18,0), (14,5), (15,3), (12,6), (9,9) and (15,0) tubes along with two semiconducting (13,11) and (16,6) ones (Figure S15d), and those from the SWNTs in the bottom brown layer to metallic (15,3) and (9,9) tubes along with semiconducting (19,5) and (15,8) ones (Figure S14d).…”

“…In the 458 nm excitation spectra (Figure 8a), the RBM peaks originating from the SWNTs in the bottom brown layer are assigned to semiconducting (13,9), (14,6), (17,0), and (13,5) tubes (Figure S14a), and those from the SWNTs in the top green layer to semiconducting (16,6), (14,6) and (13,5) tubes along with a metallic (13,13) one (Figure S15a). In the 633-nanometer excitation spectra (Figure 8b), the RBM peaks originated from the SWNTs in the top green layer are assigned to metallic (18,0), (14,5), (15,3), (12,6), (9,9) and (15,0) tubes along with two semiconducting (13,11) and (16,6) ones (Figure S15d), and those from the SWNTs in the bottom brown layer to metallic (15,3) and (9,9) tubes along with semiconducting (19,5) and (15,8) ones (Figure S14d). Even though sc-SWNTs are detected in the top green layer, their intensities are much smaller than their metallic counterparts.…”

“…In recent years, single-walled carbon nanotubes (SWNTs) have attracted much attention because of their excellent electrical, thermal, optical, and mechanical properties [1][2][3][4]. In particular, individual metallic SWNTs (m-SWNTs) and semiconducting SWNTs (sc-SWNTs) as promising materials in electrodes, logic circuits, field-effect transistors, and sensors have great potential applications [5][6][7][8][9][10][11][12]. To date, commercially available SWNTs mainly include chemical vapor deposition (CVD) yielded HiPco and CoMoCAT [8,11,13], laser-ablated [14], and arc-discharged ones [15], which invariably form large bundles composed of mixtures of 1/3 metallic and 2/3 semiconducting species [14].…”