Selective Optical Switching of Interface-Coupled Relaxation Dynamics in Carbon Nanotube–Si Heterojunctions

Ponzoni, Stefano; Galimberti, Gianluca; Sangaletti, L.; Castrucci, P.; Gobbo, Silvano Del; Morbidoni, Maurizio; Scarselli, Manuela; Pagliara, Stefania

doi:10.1021/jp506684b

Cited by 10 publications

(10 citation statements)

References 29 publications

(67 reference statements)

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“…hot electrons [14] photogenerated in the SWCNTs are ultra-fast transferred to the n-Si region, while hot holes are transported with high mobility [16] to the Au/Cr electrode through the SWCNT percolative network.…”

Section: Swcnt/si Solar Cellsmentioning

confidence: 99%

“…Furthermore, the photogenerated carriers in SWCNTs are excitons with binding energies up to 0.4 eV at room temperature [9,10], which possibly may be multiple generated [11,12]. Consequently, such photogenerated excitons are ultra-fast transferred [13][14][15] through the SWCNT percolating network and they are dissociated into high-mobility (79000 cm 2 /Vs) [16] free carriers in order to harvest their potential energy for solar cells and photodetectors. Such a dissociation is accomplished, for instance, by creating a heterojunction [17] with silicon (Si) due to the energetic band offsets greater than the SWCNT exciton binding energy [18].…”

Section: Introductionmentioning

confidence: 99%

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100% internal quantum efficiency in polychiral single-walled carbon nanotube bulk heterojunction/silicon solar cells

Nicola

Salvato

Cirillo

et al. 2017

Carbon

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Bulk heterojunction films made of polychiral single-walled carbon nanotubes (SWCNTs) form efficient\ud heterojunction solar cells with n-type crystalline silicon (n-Si), due to their superior electronic, optical,\ud and electrical properties. The films are multi-functional, since their hierarchical surface morphology\ud provides a biomimetical anti-reflective, air-stable, and hydrophobic encapsulation for Si. Also, the films\ud have a large effective area conferring them high optical absorption, which actively contribute to the solar\ud energy harvesting together with Si. Here, we report photovoltaic devices with photoconversion efficiency\ud up to 12% and a record 100% internal quantum efficiency (IQE). Such unprecedented IQE value is truly\ud remarkable and indicates that every absorbed photon from the device, at some wavelengths, generates a\ud pair of separated charge carriers, which are collected at the electrodes. The SWCNT/Si devices favor high\ud and broadband carrier photogeneration; charge dissociation of ultra-fast hot excitons; transport of\ud electrons through n-Si and high-mobility holes through the SWCNT percolative network. Moreover, by\ud varying the film thickness, it is possible to tailor the physical properties of such a two-dimensional\ud interacting system, therefore the overall device features. These results not only pave the way for lowcost,\ud high-efficient, and broadband photovoltaics, but also are promising for the development of\ud generic SWCNT-based optoelectronic applications

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Section: Swcnt/si Solar Cellsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

100% internal quantum efficiency in polychiral single-walled carbon nanotube bulk heterojunction/silicon solar cells

Nicola

Salvato

Cirillo

et al. 2017

Carbon

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“…Upon illumination, in the PV cells, holes are transferred from Si to CNTs [see, e.g., ref. 7 and Refs. therein] and therefore, as the gate voltage in a FET, the intensity of the light source (triggering the photoabsorption in Si) is expected to control and shift the Fermi level in the CNT density of states ( Fig.…”

Section: Resultsmentioning

confidence: 97%

“…In the last years experiments on hybrid heterojunctions between carbon nanotubes (CNTs) and Si wafers have demonstrated the possibility to achieve low-cost, high efficiency devices for photovoltaic (PV) applications 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 . The hybrid CNT-Si architectures can be ranked among the most promising systems for the next generation PV with power conversion efficiency (PCE) up to 17% 10 .…”

mentioning

confidence: 99%

A cross-functional nanostructured platform based on carbon nanotube-Si hybrid junctions: where photon harvesting meets gas sensing

Rigoni

Pintossi

Drera

et al. 2017

Sci Rep

Self Cite

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A combination of the functionalities of carbon nanotube (CNT)-Si hybrid heterojunctions is presented as a novel method to steer the efficiency of the photovoltaic (PV) cell based on these junctions, and to increase the selectivity and sensitivity of the chemiresistor gas sensor operated with the p-doped CNT layer. The electrical characteristics of the junctions have been tracked by exposing the devices to oxidizing (NO2) and reducing (NH3) molecules. It is shown that when used as PV cells, the cell efficiency can be reversibly steered by gas adsorption, providing a tool to selectively dope the p-type layer through molecular adsorption. Tracking of the current-voltage curve upon gas exposure also allowed to use these cells as gas sensors with an enhanced sensitivity as compared to that provided by a readout of the electrical signal from the CNT layer alone. In turn, the chemiresistive response was improved, both in terms of selectivity and sensitivity, by operating the system under illumination, as the photo-induced charges at the junction increase the p-doping of CNTs making them more sensitive to NH3 and less to NO2.

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“…On one side, single-SWCNT are excellent candidates for participating in photogeneration processes, because of their capability of absorbing light over a wide range of the solar spectrum, thanks to an energy bandgap variable from 0 to 3 eV, depending on the tube diameter and to the presence in their DOS of the vHs. On the other side, it has been recently proved [28] that SWCNTs do not merely act as a light absorber layer but, due to their extraordinary electrical conductivity (*10 6 S/cm) [29], they are also able to provide efficient transport paths for carriers, which have a very high probability to reach electrodes and generate photocurrent in devices based on CNTs photoexcitation processes [30].…”

Section: Cnts For Photovoltaic Applicationsmentioning

confidence: 99%

Semiconducting Carbon Nanotubes: Properties, Characterization and Selected Applications

Pintossi

Sangaletti

2015

Low-Dimensional and Nanostructured Materials and Devices

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Carbon nanotubes are challenging materials from the point of view of nanotechnology, because of their peculiar electrical, mechanical and optical properties arising from their monodimensional geometry. Here, the properties of carbon nanotubes are discussed, starting from their crystalline structure, in order to understand their optical, electrical and vibrational behavior. In the second section, the most popular CNT synthesis mechanism are presented, while the last section is devoted to the CNTs applications, focusing on photovoltaic and gas sensor devices.

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Selective Optical Switching of Interface-Coupled Relaxation Dynamics in Carbon Nanotube–Si Heterojunctions

Abstract: By properly tuning the photon energy of a femtosecond laser pump, we disentangle, in carbon nanotube-Si (CNT-Si) heterojunctions, the fast relaxation dynamics occurring in CNT from the slow repopulation dynamics due to hole charge transfer at the junction. In this way

Cited by 10 publications

References 29 publications

100% internal quantum efficiency in polychiral single-walled carbon nanotube bulk heterojunction/silicon solar cells

100% internal quantum efficiency in polychiral single-walled carbon nanotube bulk heterojunction/silicon solar cells

A cross-functional nanostructured platform based on carbon nanotube-Si hybrid junctions: where photon harvesting meets gas sensing

Semiconducting Carbon Nanotubes: Properties, Characterization and Selected Applications

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