Exciton diffusion, end quenching, and exciton-exciton annihilation in individual air-suspended carbon nanotubes

Ishii, Akihiro; Yoshida, Masaro; Kato, Yuichiro

doi:10.1103/physrevb.91.125427

Cited by 66 publications

(171 citation statements)

References 65 publications

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“…Next, we perform PL excitation (PLE) spectroscopy [ Fig. 1(c)] to identify the chirality (n, m) = (11, 7) by comparing the E 11 and E 22 wavelengths to tabulated data [29]. Polarization dependence of PL intensity is then measured to determine the angle of the nanotube [inset of Fig.…”

Section: Photoluminescence Spectroscopy and Time-resolved Measurementioning

confidence: 99%

“…It turns out that the dark-to-bright conversion efficiency depends strongly on the suspended length. We select (9,8) CNTs with lengths ranging from 0.5 to 4.2 µm and measure PL decay curves with E 22 excitation at a low power so that the effects of exciton-exciton annihilation can be negligible [29]. The influence of excitation and detection wavelengths as well as the excitation power dependence on the decay dynamics are discussed in the Supplemental Materials [28].…”

Section: Diffusion-limited Conversion Efficiencymentioning

confidence: 99%

“…We analyze the length dependence of the effective lifetimes with a random walk theory where the influence of end quenching is evaluated [29,31]. As the end quenching efficiency depends on the suspended length L and the generated position z of excitons, the effective lifetime is given by…”

Section: Diffusion-limited Conversion Efficiencymentioning

confidence: 99%

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High Efficiency Dark-to-Bright Exciton Conversion in Carbon Nanotubes

2019

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We report that dark excitons can have a large contribution to the emission intensity in carbon nanotubes due to an efficient exciton conversion from a dark state to a bright state. Time-resolved photoluminescence measurements are used to investigate decay dynamics and diffusion properties of excitons, and we obtain intrinsic lifetimes and diffusion lengths of bright excitons as well as diffusion coefficients for both bright and dark excitons. We find that the dark-to-bright transition rates can be considerably high, and that more than half of the dark excitons can be converted into the bright excitons. The state transition rates have a large chirality dependence with a family pattern, and the conversion efficiency is found to be significantly enhanced by adsorbed air molecules on the surface of the nanotubes. Our findings show the nontrivial significance of the dark excitons on the emission kinetics in low dimensional materials, and demonstrate the potential for engineering the dark-to-bright conversion process by using surface interactions.

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Section: Photoluminescence Spectroscopy and Time-resolved Measurementioning

confidence: 99%

Section: Diffusion-limited Conversion Efficiencymentioning

confidence: 99%

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High Efficiency Dark-to-Bright Exciton Conversion in Carbon Nanotubes

2019

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“…Time-resolved transient absorption (TA) and PL spectroscopy measurements have revealed that multiple exciton states show rapid decays due to nonradiative Auger recombination. [16][17][18][19] Nonradiative Auger recombination, which competes with exciton diffusion, determines the PL efficiency of semiconducting SWCNTs, [20][21][22][23][24] and it ensures nonclassical PL by preventing the occupation of identical exciton states. 25 Carrier doping is one of the most important techniques in semiconductors, which controls their electrical and optical properties.…”

mentioning

confidence: 99%

Review—Photophysics of Trions in Single-Walled Carbon Nanotubes

Nishihara¹,

Okano²,

Yamada³

et al. 2017

ECS J. Solid State Sci. Technol.

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The photophysics of trions in single-walled carbon nanotubes (SWCNTs) is reviewed briefly. The trion state is observed energetically below the exciton state in hole-doped SWCNTs, and shows a simple single-exponential decay. The decay dynamics of trions depends on the photoexcitation condition. The optical responses of trions can be discussed by considering the energy relaxation of the optically accessible trion state. Detailed studies of excitons, trions, and biexcitons provide a deep understanding of the material properties of SWCNTs and are required for the design of photonic devices based on SWCNTs. 3,4 which has led to accelerated experimental studies on various optical properties of SWCNTs. Electrons and holes are strongly spatially confined to diameters on the order of 1 nm, resulting in room temperature stable excitons with large binding energies in the range of 200-400 meV.5-11 The exciton dynamics thus dominates the optical properties of semiconducting SWCNTs. 5,6 High-quality carbon nanomaterials provide an excellent experimental stage for studies on photophysics of excitons and exciton complexes.The exciton structures in SWCNTs are complicated due to the intrinsic properties of graphene, their unique helical structures, and coulomb interactions. 5 The origin of the optical absorption and PL is ascribed to the dipole-allowed (bright) exciton states, and their dynamics are affected by the interplay with the dipole-forbidden (dark) exciton states. Single nanotube spectroscopy has revealed details of the intrinsic exciton properties. For example, magneto-optical studies showed that the even-parity singlet dark exciton state is located energetically below the bright exciton state.12,13 Thermalization between the bright and dark exciton states determines the temperaturedependent PL properties 12,13 and the exciton diffusion length. 14,15 Furthermore, strong spatial confinement accentuates the exciton-exciton and exciton-electron interactions. Time-resolved transient absorption (TA) and PL spectroscopy measurements have revealed that multiple exciton states show rapid decays due to nonradiative Auger recombination. [16][17][18][19] Nonradiative Auger recombination, which competes with exciton diffusion, determines the PL efficiency of semiconducting SWCNTs, [20][21][22][23][24] and it ensures nonclassical PL by preventing the occupation of identical exciton states. 25Carrier doping is one of the most important techniques in semiconductors, which controls their electrical and optical properties. In SWCNTs, carrier doping has been actively studied using chemical modification [26][27][28][29][30][31][32][33][34][35][36][37] 47 Under strong photoexcitation conditions, dissociated carriers resulting from Auger recombination can create trion states with a subsequent absorbed photon. 43 Positive and negative trion states show almost the same binding energies. 46 Time-resolved TA and PL measurements have revealed fast formation of the trion state through the exciton-hole interaction. 48,49 Active experimental stud...

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“…Despite the fact that SWCNTs have long been used as saturable absorbers [12,13] due to their large nonlinear absorption [14,15], the strong nonlinear photoluminescence (PL) has been modeled only considering a reduction in quantum efficiency due to exciton-exciton interactions and not nonlinear optical absorption due to BGR. The presence of BGR would call into question the basic understanding high fluence SWCNT PL saturation experiments [6,8,16] and the consequently extracted SWCNT properties [5,17]. BGR has been previously observed in several one-dimensional systems.…”

Section: Introductionmentioning

confidence: 99%

Independence of optical absorption on Auger ionization in single-walled carbon nanotubes revealed by ultrafast e–h photodoping

et al. 2016

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Auger-ionized free-carriers in a one-dimensional semiconductor are predicted to result in a strong band-gap renormalization. Isolated single-walled carbon nanotubes (SWCNT) under high-intensity laser irradiation exhibit strong nonlinear photoluminescence (PL) due to exciton-exciton annihilation (EEA). The presence of exciton disassociation during the rapid Auger-ionization caused by EEA would lead to a strong nonlinear absorption. By simultaneously measuring SWCNT-PL and optical absorption of isolated SWCNT clusters in the PL saturation regime, we give evidence that Augerionized excitons do not disassociate but remain bound.

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Exciton diffusion, end quenching, and exciton-exciton annihilation in individual air-suspended carbon nanotubes

Cited by 66 publications

References 65 publications

High Efficiency Dark-to-Bright Exciton Conversion in Carbon Nanotubes

High Efficiency Dark-to-Bright Exciton Conversion in Carbon Nanotubes

Review—Photophysics of Trions in Single-Walled Carbon Nanotubes

Independence of optical absorption on Auger ionization in single-walled carbon nanotubes revealed by ultrafast e–h photodoping

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