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Nanofibrillar Materials for Organic and Printable Electronics
KTH, School of Information and Communication Technology (ICT), Electronic Systems.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, organic electronics have attracted great attention due to their multiple advantages such as light weight, flexibility, large area fabrication and cost-effective production processes. The recent progress in fabricating organic electronic devices has been achieved with the development of new materials which provide competing functionalities to the electronics devices.  However, as it happens with all type of technologies, organic electronics is not free from challenges. In the latest OE-A Roadmap for organic and printed electronics (2011), the “red brick walls” were identified, and the following three main challenges were pointed out as the potential roadblocks from the material point of view: electrical performance, solution processability (especially formulations in non-toxic solvents) and environmental stability. Currently there is a significant increasing interest in optimizing or developing novel materials to meet those requirements.

 

This thesis presents processing development and study of nanofibrillar materials and deals with the optimization for its applicability for organic electronics. The overall work presented in the thesis is based on three nanofibrillar materials: Polyaniline (PANI), carbon nanotubes (CNTs) and the CNT/PANI composite. First, the solution processability of carbon nanotubes and polyaniline is studied respectively, and through covalent and non-covalent methods, stable aqueous dispersions of these materials are successfully achieved.

 

Second, a composite consisting of multi-walled carbon nanotubes (MWCNTs) and PANI with a core-shell structure is developed and characterized. The investigation of the effects of the loading and type of nanotubes incorporated in the composite material, led to understanding on the fundamental theory underlying the composite morphology. Based on those findings and by carefully optimizing the synthesis procedure, water dispersible MWCNT/PANI nanofibrillar composite is successfully synthesized becoming compatible with solution processable techniques, such as spray coating and potentially with printing technology. With the incorporation of carbon nanotubes, the nanofibrillar composite reaches conductivities 20 times higher than that of the pure polymer. Moreover, the presence of the nanotubes in the composite material decelerates up to 60 times the thermal ageing of its conductivity, making the polymer more robust and suitable for possible manufacturing processes. Furthermore, the composite material still retains the advantageous properties of PANI: electrochromism, tunable conductivities, and sensing capabilities.

 

Third, the stable dispersions of PANI, CNTs and MWCNT/PANI composite were effectively deposited by spray coating technique on several low-cost substrates (PET, PEN, polyimide and papers), and homogeneous, flexible, large-area films were fabricated. Additionally, by spraying the materials on pre-fabricated inkjet printed electrodes, a pH sensor based on the MWCNT/PANI composite and a humidity sensor based on functionalized MWCNTs capable of working at GHz range were demonstrated, which shows that the nanofibrillar materials studied in this thesis work are promising sensor materials for wireless application at ultra-high frequency (UHF) band.

 

Finally, the humidity sensor was integrated into a sensor-box demonstrating a hybrid interconnection platform where printed electronics can be seamlessly integrated with silicon-based electronics. The integration closes the gap between the two technologies, anticipating the adaption of organic electronic technologies.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , xiv, 87 p.
Series
Trita-ICT-ECS AVH, ISSN 1653-6363 ; 12:09
Keyword [en]
Organic electronics, polyaniline, carbon nanotubes, composite, spray coating, solution processability, morphology, electrical conductivity, ageing, sensor, system integration
National Category
Composite Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-116714ISBN: 978-91-7501-615-3 (print)OAI: oai:DiVA.org:kth-116714DiVA: diva2:600499
Public defence
2013-02-18, Sal D, Forum, KTH-ICT, Isafjordsgatan 39, Kista, 14:00 (English)
Opponent
Supervisors
Note

QC 20130125

Available from: 2013-01-25 Created: 2013-01-24 Last updated: 2013-01-25Bibliographically approved
List of papers
1. Characterization of acid-treated carbon nanotube thin films by means of Raman spectroscopy and field-effect response
Open this publication in new window or tab >>Characterization of acid-treated carbon nanotube thin films by means of Raman spectroscopy and field-effect response
2009 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 476, no 4-6, 258-261 p.Article in journal (Refereed) Published
Abstract [en]

By combining Raman spectroscopy with transistor transfer characteristics, acid treatment of single-walled carbon nanotubes (SWCNTs) in a mixture of concentrated HNO3/H2SO4 has been characterized. The acid treatment results in a sharp decrease in the Raman resonant signals of the metallic SWCNTs but no observable change in those of the semiconducting SWCNTs. However, the acid treatment causes disappearing gate modulation of the thin-film transistors made of the SWCNTs, contrary to what would be expected referring to the Raman results. These experimental results suggest that the energy band of the semiconducting SWCNTs is significantly affected by absorbates induced by the acid treatment.

Keyword
functionalization, purification
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-18586 (URN)10.1016/j.cplett.2009.06.041 (DOI)000267762500029 ()2-s2.0-71849098131 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
2. Morphological development of nanofibrillar composites of polyaniline and carbon nanotubes
Open this publication in new window or tab >>Morphological development of nanofibrillar composites of polyaniline and carbon nanotubes
2010 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 160, no 7-8, 664-668 p.Article in journal (Refereed) Published
Abstract [en]

Nanofibrillar composite of polyaniline (PANI)/multi-walled carbon nanotubes (MWNTs) is readily synthesized by means of conventional in situ polymerization process. It is found that the MWNT loading during polymerization has a significant influence on both the micro- and macro-scale morphological properties of the composites. At low MWNT loadings, PANI/MWNTs are formed as individual nanofibers, similar to that of the neat PANI in the absence of MWNTs. With the increase in MWNT loading, the composite exhibits granular form and becomes a continuous porous matrix at higher MWNT loadings. A possible mechanism is proposed to account for the structural variation of the composites caused by MWNTs at the different loadings.

Keyword
Composite, Carbon nanotubes, Polyaniline, Conducting polymers
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-27897 (URN)10.1016/j.synthmet.2009.12.023 (DOI)000277353800021 ()2-s2.0-77949658138 (Scopus ID)
Note

QC 20110110

Available from: 2011-01-10 Created: 2011-01-03 Last updated: 2017-12-11Bibliographically approved
3. Water dispersible carbon nanotube/polyaniline composite: study of the morphology and electrical conductivity
Open this publication in new window or tab >>Water dispersible carbon nanotube/polyaniline composite: study of the morphology and electrical conductivity
(English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290Article in journal (Other academic) Submitted
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-116708 (URN)
Note

QS 2013

Available from: 2013-01-24 Created: 2013-01-24 Last updated: 2017-12-06Bibliographically approved
4. Influence of Carbon Nanotubes on Thermal Stability of Water-Dispersible Nanofibrillar Polyaniline/Nanotube Composite
Open this publication in new window or tab >>Influence of Carbon Nanotubes on Thermal Stability of Water-Dispersible Nanofibrillar Polyaniline/Nanotube Composite
Show others...
2012 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 5, no 2, 327--335 p.Article in journal (Refereed) Published
Abstract [en]

Significant influence on the thermal stability of polyaniline (PANI) in the presence of multi-walled carbon nanotubes (MWCNTs) is reported. By means of in-situ rapid mixing approach, water-dispersible nanofibrillar PANI and composites, consisting of MWCNTs uniformly coated with PANI in the state of emeraldine salt, with a well-defined core-shell heterogeneous structure, were prepared. The de-protonation process in PANI occurs at a lower temperature under the presence of MWCNTs on the polyaniline composite upon thermal treatment. However, it is found that the presence of MWCNTs significantly enhances the thermal stability of PANI's backbone upon exposure to laser irradiation, which can be ascribed to the core-shell heterogeneous structure of the composite of MWCNTs and PANI, and the high thermal conductivity of MWCNTs.

Keyword
Polyaniline, Carbon Nanotubes, Conducting Polymers, Thermal Stability, Raman Spectroscopy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-85527 (URN)10.3390/ma5020327 (DOI)000300724000009 ()2-s2.0-84864383476 (Scopus ID)
Funder
Swedish Research Council, 2009-8068
Note
QC 20120326Available from: 2012-02-13 Created: 2012-02-13 Last updated: 2017-12-07Bibliographically approved
5. Thermal ageing of electrical conductivity in carbon nanotube/polyaniline composite films
Open this publication in new window or tab >>Thermal ageing of electrical conductivity in carbon nanotube/polyaniline composite films
2013 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 59, 270-277 p.Article in journal (Refereed) Published
Abstract [en]

The influence of carbon nanotubes on the thermal ageing effect of the electrical conductivity of composite thin films is presented. The composite thin films comprise carbon nanotube/polyaniline nanofibers. When subject to thermal treatment, the presence of nanotubes retards the loss of dopants from the polyaniline and enhances the thermal stability in electrical conductivity of the composite thin films. Specifically, an increase in temperature for the conductivity degradation and a significant reduction in the rate of the conductivity degradation of the composite thin films are observed. Upon prolonged heating, the composite thin films exhibit relative large conductivity at high nanotube content, while the polyaniline thin films become insulating.

Place, publisher, year, edition, pages
Pergamon Press, 2013
Keyword
Acid-Doped Polyaniline, Polymer Composites, Degradation, Stability
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-116712 (URN)10.1016/j.carbon.2013.03.018 (DOI)000320489300028 ()2-s2.0-84877690600 (Scopus ID)
Funder
VinnovaSwedish Research Council, 2009-8068
Note

QC 20130729. Updated from submitted to published.

Available from: 2013-01-24 Created: 2013-01-24 Last updated: 2017-12-06Bibliographically approved
6. Flexible UHF Resistive Humidity Sensors Based on Carbon Nanotubes
Open this publication in new window or tab >>Flexible UHF Resistive Humidity Sensors Based on Carbon Nanotubes
Show others...
2012 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 9, 2844-2850 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents the investigation of the resistive humidity-sensing properties of multi-walled carbon nanotubes (MWCNTs). MWCNTs functionalized by acid treatment (f-MWCNTs) exhibit rather high sensitivity in resistance toward humidity, owing to the presence of carboxylic groups on the nanotube surface. By integrating the f-MWCNTs resistor into a wireless sensor platform, flexible humidity sensors for ultra-high frequency applications are investigated. The operating frequency range of the sensor is dramatically increased from 600 MHz to 2 GHz by adjusting the resistor-electrodes' configuration. This enhancement is predominately attributed to the variation in parasitic capacitance between the resistor-electrodes.

Keyword
Carbon nanotube, flexible devices, humidity sensor, wireless sensor
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-100356 (URN)10.1109/JSEN.2012.2202390 (DOI)000307445300001 ()2-s2.0-84864910575 (Scopus ID)
Projects
the Vinn Excellence Centerthe EU project CLIP
Funder
Swedish Research Council, 2009-8068VINNOVA
Note

QC 20150623

Available from: 2012-08-07 Created: 2012-08-07 Last updated: 2017-12-07Bibliographically approved
7. System integration of smart packages using printed electronics
Open this publication in new window or tab >>System integration of smart packages using printed electronics
Show others...
2012 (English)In: Electronic Components and Technology Conference (ECTC), 2012 IEEE 62nd, IEEE , 2012, 997-1002 p.Conference paper, Published paper (Refereed)
Abstract [en]

The last decade has shown enormous interest in additive and printed electronics manufacturing technologies, especially in intelligent packaging. Scientists and engineers all over the world are developing printed organic circuits. Despite their effort, the performance and yield of all-printed devices cannot replace silicon-based devices in smart package applications. Therefore, we have developed a hybrid interconnection platform to seamlessly integrate printed electronics with silicon-based electronics, close the gap between the two technologies, and to anticipate adaption of printed electronic technologies. We studied the suitability of a printed interconnection platform by fabricating a printed sensor-box that contains printed nano-Ag-interconnections on low-temperature plastic, a printable humidity sensor based on functionalized MWCNTs, a printed battery, conventional SMDs, and a silicon-based MCU.

Place, publisher, year, edition, pages
IEEE, 2012
Series
Electronic Components & Technology Conference. Proceedings, ISSN 0569-5503
Keyword
All-printed, Functionalized, Intelligent packaging, Low temperatures, Organic circuits, Printed electronics, Scientists and engineers, Silicon-based, Silicon-based devices, Silicon-based electronics, System integration
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-74096 (URN)10.1109/ECTC.2012.6248957 (DOI)2-s2.0-84866876788 (Scopus ID)978-146731966-9 (ISBN)
Conference
2012 IEEE 62nd Electronic Components and Technology Conference, ECTC 2012; San Diego, CA;29 May 2012 through 1 June 2012
Funder
ICT - The Next Generation
Note

QC 20121121

Available from: 2012-02-02 Created: 2012-02-02 Last updated: 2013-04-15Bibliographically approved

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