Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se<sub>2</sub>-Based Solar Cells

Contreras, Miguel Á.; Barnes, Teresa M.; Lagemaat, Jao van de; Rumbles, Garry; Coutts, T. J.; Weeks, Chris; Glatkowski, Paul J.; Levitsky, Igor A.; Peltola, Jorma; Britz, David A.

doi:10.1021/jp075507b

Cited by 79 publications

(54 citation statements)

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“…These are known to be stable under flexing 7 and can be spray cast 8 , opening the way to large area deposition. While polymer 9 and graphene [10][11][12][13][14][15] films have been studied, the most common material used to date has been carbon nanotubes 7,8,[16][17][18][19][20][21][22][23][24][25][26][27] . While the cost associated with nanotubes is still a factor, it is expected to come down as demand increases to industrial levels.…”

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Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

et al. 2009

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We have used aqueous dispersions of silver nanowires to prepare thin, flexible, transparent, conducting films. The nanowires are of length and diameter close to 6.5 µm and 85 nm respectively. At low thickness, the films consist of networks but appear to become bulk-like for mean film thicknesses above ~160 nm. These films can be very transparent with optical transmittance reaching as high as 92% for low thickness. The transmittance (550 nm) decreases with increasing thickness, consistent with an optical conductivity of 6472 S/m. The films are also very uniform; the transmittance varies spatially by typically <2%. The sheet resistance decreases with increasing thickness, falling below 1 Ω/ for thicknesses above 300 nm. The DC conductivity increases from 2×10 5 S/m for very thin films before saturating at 5×10 6 S/m for thicker films.Similarly, the ratio of DC to optical conductivity increases with increasing thickness from 25 for the thinnest films, saturating at ~500 for thicknesses above ~160 nm. We believe this is the highest conductivity ratio ever observed for nanostructured films and is matched only by doped metal oxide films. These nanowire films are electromechanically very robust, with all but the thinnest films showing no change in sheet resistance when flexed over >1000 cycles. Such results make these films ideal as replacements for indium tin oxide as transparent electrodes. We have prepared films with optical transmittance and sheet resistance of 85% and 13 Ω/ respectively. This is very close to that displayed by commercially available indium tin oxide.

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Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

et al. 2009

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“…[1][2][3][4][5] TC-SWNT films are particularly attractive for photovoltaics (PV) due to their high transparency over much of the solar spectrum, excellent electrical conductivity, and the potential for inexpensive roll-to-roll processing. SWNT films have been used, by us and others, in cadmium telluride, [6] copper indium gallium diselenide, [7] and organic PV (OPV) devices. [8][9][10] In several reports, SWNTelectrodes for OPV have been prepared by filtering a sodium dodecyl sulfate (SDS)-stabilized dispersion of SWNTs to form a thin film.…”

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Ultrasmooth, Large‐Area, High‐Uniformity, Conductive Transparent Single‐Walled‐Carbon‐Nanotube Films for Photovoltaics Produced by Ultrasonic Spraying

et al. 2009

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Transparent conducting (TC) films of single-walled carbon nanotubes (SWNTs) have the potential to replace conventional TC oxides in a wide variety of optoelectronic devices. [1][2][3][4][5] TC-SWNT films are particularly attractive for photovoltaics (PV) due to their high transparency over much of the solar spectrum, excellent electrical conductivity, and the potential for inexpensive roll-to-roll processing. SWNT films have been used, by us and others, in cadmium telluride, [6] copper indium gallium diselenide, [7] and organic PV (OPV) devices. [8][9][10] In several reports, SWNTelectrodes for OPV have been prepared by filtering a sodium dodecyl sulfate (SDS)-stabilized dispersion of SWNTs to form a thin film. [9,10] The film can be released by dissolution of the filter, and then transferred to a transparent substrate.[11] This so-called ''transfer method'' produces highly transparent films with excellent conductivity, but the films possess irregular morphologies and significant roughness, which can lead to short-circuits and overall poor reproducibility during device fabrication.[12] Moreover, the process is not scalable. TC-SWNT films have also been produced for optical and electrical studies by air-brush spraying using surfactant-stabilized SWNT inks. Such films are inhomogeneous because SWNTs sprayed from surfactant solutions agglomerate on heated substrates. To move TC-SWNT electrodes beyond the proof-of-concept stage for PV and other optoelectronic applications, methods are required for producing large-area, transparent, conducting SWNT films that are smooth and homogeneous over large areas.Here, we report methods to prepare SWNT films with high transparency, electrical conductivity, and uniformity, with exceptionally low surface roughness, on arbitrarily large (6 inch Â 6 inch) substrates by ultrasonic spraying. A side-by-side comparison of OPV devices fabricated on SWNT and indiumdoped tin oxide (ITO) electrodes showed very good performance with energy-conversion efficiencies of $3.1 and 3.6%, respectively, under AM 1.5 illumination. Several factors are critical to the success of the approach. First, we prepared aqueous SWNT dispersions using a high-molecular-weight (MW $90 000) polymeric derivative of cellulose (sodium carboxymethyl cellulose (CMC)). CMC has been previously reported as an excellent agent for dispersing SWNTs in water, [13] and transparent films have been drop-cast, [14] but this is the first report of CMC-based dispersions for spraying SWNT films. A second advance is the use of ultrasonic spraying, which, when combined with the CMC-based dispersions, permits precise amounts of SWNTs to be reproducibly and uniformly dispensed over arbitrarily large areas. In fact, by measuring the weight and optical properties of films as a function of the number of deposited layers, the SWNT absorption coefficient could be accurately determined. Finally, we used SWNTs produced by laser vaporization (LV), which have lower defect densities [15,16] than tubes produced by chemical vapor deposition (CVD). Th...

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“…Early measurements showed σ DC /σ Op~1 . [4] However, film quality has improved very rapidly with a number of groups contributing in the race to better films [5][6][7][8][9][10][11][12][13][14][15][16][17]. In recent years, the best results (high σ DC /σ Op ) appear to come from films made from arc-discharge SWNTs [9,10,16,[18][19][20].…”

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The spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes

Doherty

Lyons

et al. 2009

Carbon

171

187

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The spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes, Carbon (2009Carbon ( ), doi: 10.1016Carbon ( /j.carbon.2009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPTThe spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes ACCEPTED MANUSCRIPTtransmittance and sheet resistance such as T=80% and R s =110Ω / for the t=40 nm film. Electromechanically, these films were very stable showing conductivity changes of <5% and <2% when cycled over 2000 times in compression and tension respectively.

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Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se₂-Based Solar Cells

Cited by 79 publications

References 10 publications

Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

Ultrasmooth, Large‐Area, High‐Uniformity, Conductive Transparent Single‐Walled‐Carbon‐Nanotube Films for Photovoltaics Produced by Ultrasonic Spraying

The spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes

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Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se2-Based Solar Cells

Cited by 79 publications

References 10 publications

Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

Ultrasmooth, Large‐Area, High‐Uniformity, Conductive Transparent Single‐Walled‐Carbon‐Nanotube Films for Photovoltaics Produced by Ultrasonic Spraying

The spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes

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Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se₂-Based Solar Cells