Transparent, conductive and flexible single-walled carbon nanotube films

Antti Kaskela

Transparent, conductive and flexible single-walled carbon nanotube films

Julkaisun otsikon käännös: Läpinäkyvät, johtavat ja joustavat yksiseinäiset hiilinanoputkikalvot

Antti Kaskela

Teknillisen fysiikan laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Yksiseinämäisillä hiilinanoputkilla on merkittävä sovelluspotentiaali tulevaisuuden elektroniikassa läpinäkyvänä johdemateriaalina. Nanoputkiverkot ovat merkittävästi tällä hetkellä käytössä olevia läpinäkyviä johdemateriaaleja, kuten indium-tinaoksidia, taipuisampia. Ne voidaan valmistaa laajasti saatavilla olevista raaka-aineista, kun taas hyödynnetyt indium-resurssit ovat voimakkaasti keskittyneet ja indium on ollut aggressiivisten vientirajoitusten kohteena, mikä puolestaan on lisännyt saatavuusriskejä ja aiheuttanut hinnanvaihteluita. Jotta hiilinanoputkiverkkoihin pohjautuvat materiaalit voivat kilpailla teollisissa sovelluksissa indium-tina-oksidin kanssa, niiden suorituskykyä on parannettava nykyisten teollisten materiaalien kanssa kilpailukykyiselle tasolle. Myös hiiliputkien valmistus ja prosessointimenetelmiä on kehitettävä, jotta madaltuvat tuotantokustannukset parantaisivat valmistuksen kannattavuutta. Hiilinanoputkiverkkojen suorituskyvyn parantamiseksi on tärkeää ymmärtää paremmin tärkeimpiä suorituskykyä rajoittavia tekijöitä. Tämän väitöskirjan tulokset osoittavat, että hiilinanoputkien muodostamien kimppujen pituus on erittäin merkittävä verkkojen suorituskykyyn vaikuttava tekijä. Optimoimalla aerosolipohjaisen synteesireaktorin reaktio-olosuhteet, onnistuttiin hiilinanoputkien kimppujen pituutta kasvattamaan 1.3 μm:stä 9.4 μm:iin. Kimppujen halkaisijajakaumat olivat eri kasvatusolosuhteissa päällekkäisiä, keskihalkaisijan ollessa noin 10 nm. Yksittäisten hiilinanoputkien halkaisijat olivat tyypillisesti 1.4 to 1.7 nm välillä. Pidempi kimppupituus vähentää korkean vastuksen omaavien kimppu-kimppu-liitosten lukumäärää ja pienentää näin verkon kokonaisvastusta. Kun pisimmät verkot altistettiin typpihappokäsitettelylle, onnistuttiin verkon pintavastus pienentämään tasolle 84 Ω/neliö 90 % valonläpäisyllä, tehden verkoista suorituskyvyltään kilpailukykyisiä polymeerikalvoille kasvatetun indium-tina- oksidipinnoitteen kanssa. Putkien ja kimppujen välisiä liitoksia sekä typpihappokäsittelyn vaikutusta tutkittiin käyttäen johtavaa atomivoimamikroskopiaa. Käsittelemättömien liitoksien liitosvastukset vaihtelivat 29 kΩ ja 532 kΩ välillä, pääosin yksittäisistä nanoputkista ja halkaisijaltaan pienistä, alle 5 nm kimpuista, koostuvalle näytepopulaatiolle. Liitosvastuksen havaittiin pienenevän kasvavan putki- ja kimppuhalkaisijan mukana. Liitoksen geometrialla havaittiin olevan merkittävä vaikutus liitosvastukseen ja X-tyyppiset liitokset omasivat keskimäärin 180 kΩ liitosvastuksen, kun taas Y-tyyppisten liitoksen keskimääräinen vastus oli 60 kΩ. Kun X-tyyppiset liitokset käsiteltiin voimakkaalla typpihapolla, liitosvastus pieneni tekijällä 3x, kun taas pituusvastus pysyi lähes vakiona noin 8 kΩ/μm tasolla. Tulosten mukaan typpihappokäsittely parantaa verkon suorituskykyä lähinnä pienentämällä liitosvastuksia. Lisäksi tässä väitöskirjassa tutkittiin useita hiilinanoputkiverkkojen sovellusalueita ja niiden toteuttamisessa tarvittavia tekniikoita. Osana työtä kehitettiin uusi, huoneenlämpötilassa toimiva valmistusmenetelmä hiiliputkiverkkojen siirtämiseen keräyssuodattimelta sovelluksissa tarvittaville pohjamateriaaleille. Menetelmän osoitettiin mahdollistavan eri paksuuksien hiilinanoputkiverkkojen nopea ja suoraviivainen siirto laajalle joukolle pohjamateriaaleja, mukaan lukien joustavat polymeerit, lasi, pii sekä metallikalvot. Menetelmän merkittävä etu on, että se poistaa tarpeen haitallisille ja aikaa vieville puhdistus- ja dispersointikäsittelyille, joita tarvitaan muiden hiilinanoputkien keräys- ja prosessointimenetelmien kanssa ja mahdollistaa siten hiiliputkien korkean ominaisjohtavuuden hyödyntämisen. Osana väitöskirjaa valmistettiin myös uudenlaisia itsekantavia nanoputkiverkkoja. Hiilinanoputkiverkkoja käytettiin lisäksi myös joustavina väriaineherkistetyn aurinkokennon vastaelektrodimateriaalina. Yhdistämällä hiilinanoputkiverkko elektropolymerisoidun PEDOT-polymeerin kanssa saavutettiin standardia platinakatalyyttiä vastaava suorituskyky, parhaimmillaan 4 % energiakonversiotehokkuudella. Viimeisenä aihealueena tutkittiin hiilinanoputkien ja amorfisten plasmakasvatuksella valmistettujen hiilipinnoitteiden yhdistämistä hybridirakenteeksi. Hiilipinnoitteen käyttö paransi merkittävästi hiilinanoputkiverkon mekaanista kestävyyttä, hybridimateriaalin säilyttäessä sähköisen johtavuuden sekä optisen läpinäkyvyytensä.

Julkaisun otsikon käännös	Läpinäkyvät, johtavat ja joustavat yksiseinäiset hiilinanoputkikalvot
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Kauppinen, Esko, Vastuuprofessori Nasibulin, Albert G., Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-5458-2
Sähköinen ISBN	978-952-60-5459-9
Tila	Julkaistu - 2013
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

yksiseinäinen hiilinanoputki
liitosvastus
läpinäkyvä johdekalvo
verkko
sovellukset

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-5459-9

Siteeraa tätä

@phdthesis{774424d8200447cb9e6a093b4d0ce37c,

title = "Transparent, conductive and flexible single-walled carbon nanotube films",

abstract = "Single-walled carbon nanotube (SWCNT) networks have a large application potential for future electronics as transparent conductive ﬁlms. SWCNT networks (SWCNT-N) offer improved ﬂexibility when compared to the current industry standard transparent conductive ﬁlms (TCF), an example of which is indium tin oxide (ITO). SWCNTs can be synthesised from abundant raw materials, whereas indium supply is limited and has been a target of aggressive trade policies, thus increasing supply risks and price volatility. In order to make the SWCNT-Ns suitable for industrial applications, their performance must be made competitive with ITO and other TCF materials, whilst their manufacturing costs have to be minimised. Understanding the performance limiting factors is important when it comes to the development of high performance SWCNT networks. The results presented here show that the bundle length has a major impact on the electrical performance of SWCNT networks. Optimisation of SWCNT growth conditions in aerosol-CVD reactors used for SWCNT synthesis led to an increase in SWCNT bundle length from 1.3 μm to 9.4 μm. Bundle diameter distributions were found to overlap, with mean bundle diameter measuring approximately 10 nm, and mean SWCNT diameters ranging from 1.4 to 1.7 nm. The increased bundle length led to a reduction in the number of the highly resistive bundle-bundle contacts and to improved performance. When the SWCNT-TCFs were chemically doped by nitric acid, sheet resistance was reduced down to 84 Ω/sq. at 90% transparency, thus making the SWCNT TCFs competitive with ITO on polymer ﬁlms. The intertube and interbundle contact resistances together with the effect of nitric acid treatment were studied by using conductive atomic force microscopy. The contact resistance values of pristine junctions were within the range of 29 kΩ - 532 kΩ for contacts between individual tubes and small bundles with less than 5 nm diameter. The contact resistance decreased with increasing tube or bundle diameter. Contact morphology had a major impact on the contact resistance values as X- contacts exhibited higher mean contact resistance of 180 kΩ, while the Y-contacts had mean contact resistance of 60 kΩ. When the contacts were exposed to strong nitric acid, the mean contact resistance was reduced by a factor of 3, although the length resistivity remained largely unchanged at around 8 kΩ/μm. The results indicate that the contact morphology and the diameter of contacting SWCNTs and bundles had a signiﬁcant impact on the electrical transport across the contacts and that the nitric acid treatment mainly affected the network performance by modulating the contacts and reducing their contact resistances. Furthermore, a novel room-temperature press transfer technique was developed. This dry, ambient temperature deposition method allowed for the rapid and direct deposition of variable thickness SWCNT networks to a wide range of substrates, from ﬂexible polymers to glass, silicon and metals. The developed process eliminates harsh and detrimental puriﬁcation and dispersion steps, thus maintaining the high intrinsic performance of SWCNTs. Fabrication of novel freestanding SWCNT networks was also demonstrated. The freestanding SWCNT networks can be used for a wide range of novel applications. The aerosol-CVD synthesized SWCNTs were also demonstrated as ﬂexible counter-electrodes in dye-sensitised solar cells. The SWCNT-network was combined with electrochemically deposited PEDOT, reaching comparable performance with standard platinum catalyst with energy conversion efﬁciencies of up to 4%. Fabrication and properties of hybrid materials consisting of SWCNT networks coated with amorphous carbon deposited by low energy plasma were studied. The carbon coating improved the mechanical durability of SWCNT ﬁlms under nanoindentation and scratching.",

keywords = "single-walled carbon nanotube, contact resistance, transparent conductive film, network, applications, yksisein{\"a}inen hiilinanoputki, liitosvastus, l{\"a}pin{\"a}kyv{\"a} johdekalvo, verkko, sovellukset, single-walled carbon nanotube, contact resistance, transparent conductive film, network, applications",

author = "Antti Kaskela",

year = "2013",

language = "English",

isbn = "978-952-60-5458-2",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "197",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Transparent, conductive and flexible single-walled carbon nanotube films

AU - Kaskela, Antti

PY - 2013

Y1 - 2013

N2 - Single-walled carbon nanotube (SWCNT) networks have a large application potential for future electronics as transparent conductive ﬁlms. SWCNT networks (SWCNT-N) offer improved ﬂexibility when compared to the current industry standard transparent conductive ﬁlms (TCF), an example of which is indium tin oxide (ITO). SWCNTs can be synthesised from abundant raw materials, whereas indium supply is limited and has been a target of aggressive trade policies, thus increasing supply risks and price volatility. In order to make the SWCNT-Ns suitable for industrial applications, their performance must be made competitive with ITO and other TCF materials, whilst their manufacturing costs have to be minimised. Understanding the performance limiting factors is important when it comes to the development of high performance SWCNT networks. The results presented here show that the bundle length has a major impact on the electrical performance of SWCNT networks. Optimisation of SWCNT growth conditions in aerosol-CVD reactors used for SWCNT synthesis led to an increase in SWCNT bundle length from 1.3 μm to 9.4 μm. Bundle diameter distributions were found to overlap, with mean bundle diameter measuring approximately 10 nm, and mean SWCNT diameters ranging from 1.4 to 1.7 nm. The increased bundle length led to a reduction in the number of the highly resistive bundle-bundle contacts and to improved performance. When the SWCNT-TCFs were chemically doped by nitric acid, sheet resistance was reduced down to 84 Ω/sq. at 90% transparency, thus making the SWCNT TCFs competitive with ITO on polymer ﬁlms. The intertube and interbundle contact resistances together with the effect of nitric acid treatment were studied by using conductive atomic force microscopy. The contact resistance values of pristine junctions were within the range of 29 kΩ - 532 kΩ for contacts between individual tubes and small bundles with less than 5 nm diameter. The contact resistance decreased with increasing tube or bundle diameter. Contact morphology had a major impact on the contact resistance values as X- contacts exhibited higher mean contact resistance of 180 kΩ, while the Y-contacts had mean contact resistance of 60 kΩ. When the contacts were exposed to strong nitric acid, the mean contact resistance was reduced by a factor of 3, although the length resistivity remained largely unchanged at around 8 kΩ/μm. The results indicate that the contact morphology and the diameter of contacting SWCNTs and bundles had a signiﬁcant impact on the electrical transport across the contacts and that the nitric acid treatment mainly affected the network performance by modulating the contacts and reducing their contact resistances. Furthermore, a novel room-temperature press transfer technique was developed. This dry, ambient temperature deposition method allowed for the rapid and direct deposition of variable thickness SWCNT networks to a wide range of substrates, from ﬂexible polymers to glass, silicon and metals. The developed process eliminates harsh and detrimental puriﬁcation and dispersion steps, thus maintaining the high intrinsic performance of SWCNTs. Fabrication of novel freestanding SWCNT networks was also demonstrated. The freestanding SWCNT networks can be used for a wide range of novel applications. The aerosol-CVD synthesized SWCNTs were also demonstrated as ﬂexible counter-electrodes in dye-sensitised solar cells. The SWCNT-network was combined with electrochemically deposited PEDOT, reaching comparable performance with standard platinum catalyst with energy conversion efﬁciencies of up to 4%. Fabrication and properties of hybrid materials consisting of SWCNT networks coated with amorphous carbon deposited by low energy plasma were studied. The carbon coating improved the mechanical durability of SWCNT ﬁlms under nanoindentation and scratching.

AB - Single-walled carbon nanotube (SWCNT) networks have a large application potential for future electronics as transparent conductive ﬁlms. SWCNT networks (SWCNT-N) offer improved ﬂexibility when compared to the current industry standard transparent conductive ﬁlms (TCF), an example of which is indium tin oxide (ITO). SWCNTs can be synthesised from abundant raw materials, whereas indium supply is limited and has been a target of aggressive trade policies, thus increasing supply risks and price volatility. In order to make the SWCNT-Ns suitable for industrial applications, their performance must be made competitive with ITO and other TCF materials, whilst their manufacturing costs have to be minimised. Understanding the performance limiting factors is important when it comes to the development of high performance SWCNT networks. The results presented here show that the bundle length has a major impact on the electrical performance of SWCNT networks. Optimisation of SWCNT growth conditions in aerosol-CVD reactors used for SWCNT synthesis led to an increase in SWCNT bundle length from 1.3 μm to 9.4 μm. Bundle diameter distributions were found to overlap, with mean bundle diameter measuring approximately 10 nm, and mean SWCNT diameters ranging from 1.4 to 1.7 nm. The increased bundle length led to a reduction in the number of the highly resistive bundle-bundle contacts and to improved performance. When the SWCNT-TCFs were chemically doped by nitric acid, sheet resistance was reduced down to 84 Ω/sq. at 90% transparency, thus making the SWCNT TCFs competitive with ITO on polymer ﬁlms. The intertube and interbundle contact resistances together with the effect of nitric acid treatment were studied by using conductive atomic force microscopy. The contact resistance values of pristine junctions were within the range of 29 kΩ - 532 kΩ for contacts between individual tubes and small bundles with less than 5 nm diameter. The contact resistance decreased with increasing tube or bundle diameter. Contact morphology had a major impact on the contact resistance values as X- contacts exhibited higher mean contact resistance of 180 kΩ, while the Y-contacts had mean contact resistance of 60 kΩ. When the contacts were exposed to strong nitric acid, the mean contact resistance was reduced by a factor of 3, although the length resistivity remained largely unchanged at around 8 kΩ/μm. The results indicate that the contact morphology and the diameter of contacting SWCNTs and bundles had a signiﬁcant impact on the electrical transport across the contacts and that the nitric acid treatment mainly affected the network performance by modulating the contacts and reducing their contact resistances. Furthermore, a novel room-temperature press transfer technique was developed. This dry, ambient temperature deposition method allowed for the rapid and direct deposition of variable thickness SWCNT networks to a wide range of substrates, from ﬂexible polymers to glass, silicon and metals. The developed process eliminates harsh and detrimental puriﬁcation and dispersion steps, thus maintaining the high intrinsic performance of SWCNTs. Fabrication of novel freestanding SWCNT networks was also demonstrated. The freestanding SWCNT networks can be used for a wide range of novel applications. The aerosol-CVD synthesized SWCNTs were also demonstrated as ﬂexible counter-electrodes in dye-sensitised solar cells. The SWCNT-network was combined with electrochemically deposited PEDOT, reaching comparable performance with standard platinum catalyst with energy conversion efﬁciencies of up to 4%. Fabrication and properties of hybrid materials consisting of SWCNT networks coated with amorphous carbon deposited by low energy plasma were studied. The carbon coating improved the mechanical durability of SWCNT ﬁlms under nanoindentation and scratching.

KW - single-walled carbon nanotube

KW - contact resistance

KW - transparent conductive film

KW - network

KW - applications

KW - yksiseinäinen hiilinanoputki

KW - liitosvastus

KW - läpinäkyvä johdekalvo

KW - verkko

KW - sovellukset

KW - single-walled carbon nanotube

KW - contact resistance

KW - transparent conductive film

KW - network

KW - applications

M3 - Doctoral Thesis

SN - 978-952-60-5458-2

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Transparent, conductive and flexible single-walled carbon nanotube films

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

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