Hybridized C–O–Si Interface States at the Origin of Efficiency Improvement in CNT/Si Solar Cells

Ponzoni, Stefano; Achilli, Simona; Pintossi, Chiara; Drera, Giovanni; Sangaletti, L.; Castrucci, P.; Crescenzi, M. De; Pagliara, Stefania

doi:10.1021/acsami.7b01766

Cited by 13 publications

(5 citation statements)

References 33 publications

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“…Before our 2012 report on the early progress in this field, and the recent efficiency and active area records, the first report of carbon nanotube–silicon heterojunctions being used specifically for solar cells was by Wei et al in 2007 . The overall power conversion efficiency (PCE) of Wei et al's device was around 1.3% but, as can be seen in Figure 1 and in Table S1 of the Supporting Information, very rapid efficiency gains have been made since then, as might be expected for an architecture based on the already mature field of silicon photovoltaics (PV). However, there is still significant room for improvement in the maximum efficiency of proof‐of‐principle laboratory cells.…”

Section: Introductionmentioning

confidence: 97%

“…However, in direct contradiction is a theoretical study by Imran and Butt comparing detailed physics‐based modeling of nanomaterial–insulator–semiconductor photovoltaics to the experimental results of Jia et al and showing good correlation between the predicted and experimentally measured variations in efficiency with oxide thickness, yielding a peak in efficiency at around 12 Å (estimated by comparison of oxygen and silicon Auger signals) . In relevant related work, XPS studies by Pintossi et al have shown that the stoichiometry of the oxide can be critical to performance, and recent work from Ponzoni et al has suggested the intriguing possibility of direct COSi bond formation between the nanotubes and the silicon during the sequence of treatments that follow deposition of the nanotubes on the surface (though this is currently only a theoretical model—the experimental evidence is limited to an interpretation of peak fitting to the high‐energy components of the C1s XPS peak). If it is indeed true that COSi bonds are formed, this would have broad implications for the carbon nanotube–silicon interface ranging far beyond their use in photovoltaics.…”

Section: Introductionmentioning

confidence: 99%

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Advances in Carbon Nanotube–Silicon Heterojunction Solar Cells

Tune

Flavel

2018

Advanced Energy Materials

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in this field as represented in Figure 2 and is broadly divided into two halves. The first half presents some essential background information on carbon nanotubes, particularly in relevance to their role in these kinds of solar cells, as well as a consideration of aspects such as thin film properties, device stability, scale-up, and operating mechanism, while the second half deals with the factors involved in improving performance.This review has been constrained almost exclusively to covering developments in the field of carbon nanotubes interfaced with monocrystalline silicon, though the field is also informed by other work being done in the associated areas of graphene-silicon and conducting polymer-silicon solar cells, as well as the use of nanotube films interfaced with polycrystalline silicon and other semiconductors, perovskites, organic photovoltaics, and more. This is partly in the interests of being able to provide a useful and informative level of technical detail while keeping the work to a manageable and digestible size both for those already working in the field and those new to it. It is also because although there are many parallels between, for example, the nanotube-silicon and polymer-silicon or graphene-silicon works, there are several important and fundamental differences, not the least of which may be the potential complexity/diversity of the operating mechanism(s) in the nanotube-silicon case. For information on these and other related types of photovoltaic device architectures incorporating carbon nanotubes, we refer the reader to Zielke et al., [49] Wang et al., [50] and Arnold et al., [51] as well as Li et al. [52] which also includes an overview of the carbon nanotube-silicon architecture as a part of the broader carbon-silicon theme. Table S1 of the Supporting Information provides a detailed and comprehensive list of published works in the carbon nanotube-silicon field along with various performance measurements, device structure parameters, and material properties. BackgroundAlthough once an exotic, poorly understood, and difficult to obtain material, carbon nanotubes are now relatively well known, well understood, and widely available from commercial suppliers. Briefly, single-walled carbon nanotubes (SWCNT) are very high aspect ratio cylinders of graphene in which the Heterojunctions of carbon nanotubes interfaced with silicon respond to light illumination and can be operated in the power regime as solar cells. Very significant advances have been made in the last 5 years both in terms of headline performance values and in fundamental understanding of the underlying operating principles, as well as the sophistication of the devices and studies being reported. The body of literature is growing rapidly, and the latest power conversion efficiency and active area records have now reached over 17% and 2 cm 2 , respectively. Thus, the authors believe that it is now a useful time for an evaluation of the current state-of-the-art and challenges going forward, as well as for a comprehensively ...

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Advances in Carbon Nanotube–Silicon Heterojunction Solar Cells

Tune

Flavel

2018

Advanced Energy Materials

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“…One prerequisite for engineering SWNT based-optical devices is the understanding of their photophysics on an ultrafast timescale. For instance, tracking ultrafast charge transfer processes between different SWNTs or SWNT-Si heterojunctions can provide important information for designing SWTN-based photovoltaic devices 8 , 9 . Furthermore, the ultrafast dynamics of SWNTs offers reliable optical switching mechanism for laser mode-locking 3 , 4 , 10 – 12 .…”

Section: Introductionmentioning

confidence: 99%

Bandgap renormalization in single-wall carbon nanotubes

Zhu

Liu

et al. 2017

Sci Rep

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Single-wall carbon nanotubes (SWNTs) have been extensively explored as an ultrafast nonlinear optical material. However, due to the numerous electronic and morphological arrangements, a simple and self-contained physical model that can unambiguously account for the rich photocarrier dynamics in SWNTs is still absent. Here, by performing broadband degenerate and non-degenerate pump-probe experiments on SWNTs of different chiralities and morphologies, we reveal strong evidences for the existence of bandgap renormalization in SWNTs. In particularly, it is found that the broadband transient response of SWNTs can be well explained by the combined effects of Pauli blocking and bandgap renormalization, and the distinct dynamics is further influenced by the different sensitivity of degenerate and non-degenerate measurements to these two concurrent effects. Furthermore, we attribute optical-phonon bath thermalization as an underlying mechanism for the observed bandgap renormalization. Our findings provide new guidelines for interpreting the broadband optical response of carbon nanotubes.

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“…The energy difference between the excited states sampled by the current in {Mn 4 } (27 μeV) and in {Co 4 } (100 μeV at B = 8 T) is orders of magnitude smaller than other processes known to cause RTS in CNT devices [43][44][45]. Note that these transitions do not involve spin flips, as those would require comparably large energies, since states with different spin configuration lie ∼2 orders of magnitude higher in energy (see Sec.…”

Section: Theoretical Modelmentioning

confidence: 96%