Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp3 Defect States
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Duke Univ., Durham, NC (United States). Dept. of Chemistry and French Family Science Center
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry and Biochemistry
- North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry and Biochemistry
Photoluminescent sp3 defect states introduced to single wall carbon nanotubes (SWCNTs) through low-level covalent functionalization create new photophysical behaviors and functionality as a result of defect sites acting as exciton traps. Evaluation of relaxation dynamics in varying dielectric environments can aid in advancing a more complete description of defect-state relaxation pathways and electronic structure. For this study, we exploit helical wrapping polymers as a route to suspending (6,5) SWCNTs covalently functionalized with 4-methoxybenzene in solvent systems including H2O, D2O, methanol, dimethylformamide, tetrahydrofuran, and toluene, spanning a range of dielectric constants from 80 to 3. Defect-state photoluminescence decays were measured as a function of emission wavelength and solvent environment. Emission decays are biexponential, with short lifetime components on the order of 65 ps and long components ranging from around 100 to 350 ps. Both short and long decay components increase as emission wavelength increases, while only the long lifetime component shows a solvent dependence. We demonstrate that the wavelength dependence is a consequence of thermal detrapping of defect-state excitons to produce mobile E11 excitons, providing an important mechanism for loss of defect-state population. Deeper trap states (i.e., those emitting at longer wavelengths) result in a decreased rate for thermal loss. The solvent-independent behavior of the short lifetime component is consistent with its assignment as the characteristic time for redistribution of exciton population between bright and dark defect states. Furthermore, the solvent dependence of the long lifetime component is shown to be consistent with relaxation via an electronic to vibrational energy transfer mechanism, in which energy is resonantly lost to solvent vibrations in a complementary mechanism to multiphonon decay processes.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- AC52-06NA25396; SC0001517
- OSTI ID:
- 1461401
- Report Number(s):
- LA-UR--18-23574
- Journal Information:
- ACS Nano, Journal Name: ACS Nano Journal Issue: 8 Vol. 12; ISSN 1936-0851
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Solvatochromism of near infrared photoluminescence from doped sites of locally functionalized single-walled carbon nanotubes
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journal | January 2019 |
Intrinsic limits of defect-state photoluminescence dynamics in functionalized carbon nanotubes
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journal | January 2019 |
Exciton relaxation in carbon nanotubes via electronic-to-vibrational energy transfer
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journal | October 2019 |
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