Saturation of the Photoluminescence at Few-Exciton Levels in a Single-Walled Carbon Nanotube under Ultrafast Excitation

Xiao, Yee-Fang; Nhan, Tam; Wilson, Mark W.; Fraser, James M.

doi:10.1103/physrevlett.104.017401

Cited by 58 publications

(112 citation statements)

References 30 publications

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“…Hence, we would expect a nanotube suspended in air to have a different diffusion constant from a nanotube on a surface or in a medium. 18,21,32 In the context of a sensor, local trapping would decrease the absolute change in the nanotube's fluorescence in response to defects. It would, however, increase the range of the sensor and provide better correlation between the number of defects on the nanotube and the fluorescence intensity.…”

Section: N(t)mentioning

confidence: 99%

The Role of Length and Defects on Optical Quantum Efficiency and Exciton Decay Dynamics in Single-Walled Carbon Nanotubes

Harrah

Swan

2010

ACS Nano

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). The existence of a dark exciton level below the bright exciton band has been proposed as an explanation for low quantum efficiency.9 Spataru et al. showed that this splitting has minimal effect at room temperature, and the more important effect is the thermal momentum blocking of the radiative transition. 10The relatively low values of the quantum efficiency show that it is the nonradiative decay rate that dominates over the radiative decay rate. There are several nonradiative decay mechanisms proposed in the literature. At high fluences, excitonϪexciton Auger deexcitation has been suggested. 11,12 Furthermore, excitons in doped semiconducting nanotubes can decay via electronϪphonon interactions. 13 However, for undoped nanotubes in the linear regime, the main nonradiative decay mechanism is exciton diffusion to quenching sites, such as structural defects, adsorbate molecules, or the ends of the nanotube. 14Ϫ16 Stepwise fluorescence quenching in carbon nanotubes in response to changes to the nanotube's environment 16Ϫ18 can clearly also be utilized in sensor applications, such as biological sensors, ideally capable of detecting single molecules. 19The diffusion constant is the main parameter of the diffusion model, but it is not well-known. Experimentally extracted values of the diffusion constant range over 3 orders of magnitude, from 0.1 to 100 cm 2 /s. 12,16,18,20,21 Environment, chirality variation, length distributions, sample quality, and the presence of bundling introduce complexities in the behavior of the optical properties of nanotubes. Therefore, it is important to first examine the expected behavior of an individual nanotube with wellcontrolled static or dynamic quenching defects as the only interaction with the environment.In this paper, we assume that the observed diffusive behavior arises from random walks by excitons and perform Monte Carlo simulations of these random walks to model the fluorescence from nanotubes under uniform excitation (see Detailed Methods). From these simulations, we obtain the time-resolved, spatially resolved, and integrated quantum efficiency for nanotubes in the presence of perfectly quenching defects and of varying lengths. We show

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Section: N(t)mentioning

confidence: 99%

The Role of Length and Defects on Optical Quantum Efficiency and Exciton Decay Dynamics in Single-Walled Carbon Nanotubes

Harrah

Swan

2010

ACS Nano

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“…Evidence of EEA has been observed in the form of pump-dependent variations in PL decay dynamics [11][12][13] as well as saturation behaviors of PL [14,15] and transient absorption signals [20]. Many attempts have also been made to determine the exciton diffusion length, L D , in SWCNTs [8,[16][17][18][19], revealing values ranging from nanometers [9] to hundreds of nanometers [10,16,19].…”

mentioning

confidence: 99%

Influences of Exciton Diffusion and Exciton-Exciton Annihilation on Photon Emission Statistics of Carbon Nanotubes

Roslyak

Duque

et al. 2015

Phys. Rev. Lett.

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Pump-dependent photoluminescence imaging and 2 nd order photon correlation studies have been performed on individual single-walled carbon nanotubes (SWCNTs) at room temperature that enable the extraction of both the exciton diffusion constant and the Auger recombination coefficient. A linear correlation between these is attributed to the effect of environmental disorder in setting the exciton mean free-path and capture-limited Auger recombination at this lengthscale.A suppression of photon antibunching is attributed to creation of multiple spatially nonoverlapping excitons in SWCNTs whose diffusion length is shorter than the laser spot size. We conclude that complete antibunching at room temperature requires an enhancement of the exciton-exciton annihilation rate that may become realizable in SWCNTs allowing for strong exciton localization.

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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.…”

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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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Saturation of the Photoluminescence at Few-Exciton Levels in a Single-Walled Carbon Nanotube under Ultrafast Excitation

Cited by 58 publications

References 30 publications

The Role of Length and Defects on Optical Quantum Efficiency and Exciton Decay Dynamics in Single-Walled Carbon Nanotubes

The Role of Length and Defects on Optical Quantum Efficiency and Exciton Decay Dynamics in Single-Walled Carbon Nanotubes

Influences of Exciton Diffusion and Exciton-Exciton Annihilation on Photon Emission Statistics of Carbon Nanotubes

Review—Photophysics of Trions in Single-Walled Carbon Nanotubes

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