In one-dimensional semiconductors such as conjugated polymers and semiconducting single-walled carbon nanotubes(s-SWCNTs),injected charge carriers(electrons or holes)can have profound impacts on both electronic conduc...In one-dimensional semiconductors such as conjugated polymers and semiconducting single-walled carbon nanotubes(s-SWCNTs),injected charge carriers(electrons or holes)can have profound impacts on both electronic conductivity and optical spectra,even at low carrier densities.Understanding charge-related spectral features is a key fundamental challenge with important technological implications.Here,we employ a systematic suite of experimental and theoretical tools to understand the mid-infrared charge signatures of heavily p-type doped polymer-wrapped s-SWCNTs.Across a broad range of nanotube diameters,we find that hole charge carriers induce strong Fano anti-resonances in mid-infrared transmission spectra that correspond to defect-related(D-band)and in-plane tangential(G-band)Raman-active vibrational modes,along with antiresonances arising from infrared(IR)-active polymer and SWCNT modes.We employ^(13)C isotope-labeled s-SWCNTs and a removable wrapping polymer to clarify the relative intensities,energies,and sources of all observed anti-resonances.Simulations performed with the“amplitude mode model”are used to quantitatively reproduce Raman spectra and also help to explain the outsized intensity of the D-band anti-resonance,relative to the G-band,observed for both moderately and degenerately doped s-SWCNTs.The results provide a framework for future studies of ground-and excited-state charge carriers in s-SWCNTs and a variety of low-dimensional materials.展开更多
文摘In one-dimensional semiconductors such as conjugated polymers and semiconducting single-walled carbon nanotubes(s-SWCNTs),injected charge carriers(electrons or holes)can have profound impacts on both electronic conductivity and optical spectra,even at low carrier densities.Understanding charge-related spectral features is a key fundamental challenge with important technological implications.Here,we employ a systematic suite of experimental and theoretical tools to understand the mid-infrared charge signatures of heavily p-type doped polymer-wrapped s-SWCNTs.Across a broad range of nanotube diameters,we find that hole charge carriers induce strong Fano anti-resonances in mid-infrared transmission spectra that correspond to defect-related(D-band)and in-plane tangential(G-band)Raman-active vibrational modes,along with antiresonances arising from infrared(IR)-active polymer and SWCNT modes.We employ^(13)C isotope-labeled s-SWCNTs and a removable wrapping polymer to clarify the relative intensities,energies,and sources of all observed anti-resonances.Simulations performed with the“amplitude mode model”are used to quantitatively reproduce Raman spectra and also help to explain the outsized intensity of the D-band anti-resonance,relative to the G-band,observed for both moderately and degenerately doped s-SWCNTs.The results provide a framework for future studies of ground-and excited-state charge carriers in s-SWCNTs and a variety of low-dimensional materials.
