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Song, Man
Publications (9 of 9) Show all publications
Song, M. (2019). Graphene Based Inks for Printed Electronics. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Graphene Based Inks for Printed Electronics
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The outstanding properties of graphene make it attractive ink filler for conductive inks which plays an important role in printed electronics. This thesis focuses on the ink formulation based on graphene and graphene oxide (GO).

Liquid phase exfoliation of graphite is employed to prepare graphene dispersions, i.e., shear- and electrochemical exfoliation. High concentration graphene dispersions with small size, few-layer graphene platelets are obtained by both methods. With the addition of ethyl cellulose stabilizer, shear-exfoliated graphene platelets in NMP were successfully inkjet printed on different substrates. The printed graphene film with electrical conductivity of ~3^104 S/m was obtained after annealing at 350 °C for one hour. Alternatively, the electrochemically exfoliated graphene nano-platelets were collected and redispersed in DMF to form inks. The printed film of conductivity ~2.5^103 S/m was obtained after annealing at 300 °C for one hour.

Water based GO/Ag hybrid inks were developed for screen printing. When high concentration GO aqueous dispersion was mixed with reactive silver ink, the viscosity of the mixture increased instantly to above 1000 cP as a result of reactions between oxygen functional groups (OFGs) on GO sheets and ingredients in the reactive silver ink. When the screen printed lines with different GO:Ag ratios were annealed in air, the conductivity of the resultant reduced graphene oxide/silver nanoparticles (RGO/AgNPX) composites decreased as silver content increased. As oxygen enriched compounds in RGO/AgNPX composites were detected, we proposed that AgOx compounds were generated on the AgNPs surface, which raised the contact resistance between AgNPs and RGO flakes. To solve this problem, the printed patterns were instead annealed in reducing gas (Ar/H2 5%). The electrical conductivity ~2.0^104 S/m was then achieved.

Furthermore, the reduction of GO using ammonium formate as reducing reagent was investigated. When applying a hydrothermal method, ammonium formate shows excellent reduction ability, surpassing the widely used reducing agent, L-ascorbic acid, under same condition. Elemental analysis shows the C/O ratio of RGO as high as ~11 and most OFGs were removed in the reduction process. Meanwhile, incorporated nitrogen atoms introduced active sites in resultant RGO, making it a promising electrocatalyst for oxygen reduction reaction.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 64
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1780
Keywords
Exfoliation, Graphene inks, Inkjet printing, Screen printing, GO/Ag hybrid inks, Leuckart reaction, Reduction.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-377697 (URN)978-91-513-0588-2 (ISBN)
Public defence
2019-04-25, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2019-04-01 Created: 2019-02-25 Last updated: 2019-05-07
Song, M., Tahershamsi, L., Zhao, J., Zhang, Z.-B. & Grennberg, H. (2018). Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction. ChemNanoMat, 4(11), 1145-1152
Open this publication in new window or tab >>Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction
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2018 (English)In: ChemNanoMat, ISSN 2199-692X, Vol. 4, no 11, p. 1145-1152Article in journal (Refereed) Published
Abstract [en]

Abstract Graphene oxide (GO) undergoes a rapid gelation process in the presence of ammonium hydroxide and formic acid at room temperature which is promoted by ultrasonication. Infrared and X-ray photoelectron spectroscopy proved partial reduction of GO and nitrogen incorporation, resulting from sonication-promoted Leuckart reactions at GO carbonyl groups. The amine groups produced via Leuckart reactions undergo further reactions that result in salt bridges with carboxylic groups and covalent cross-links, both of which contribute to the stabilization of the resulting hydrogel. The resultant GO hydrogel exhibits enhanced thermal stability.

Keywords
Gelation, graphene oxide, hydrogels, Leuckart reaction, ultrasonication
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-363972 (URN)10.1002/cnma.201800286 (DOI)000452398900006 ()
Funder
Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, No. 621-2014-5596Knut and Alice Wallenberg Foundation
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-02-25
Zhao, J., Song, M., Wen, C., Majee, S., Yang, D., Wu, B., . . . Zhang, Z.-B. (2018). Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing. Journal of Micromechanics and Microengineering, 28(3), Article ID 035006.
Open this publication in new window or tab >>Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing
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2018 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 28, no 3, article id 035006Article in journal (Refereed) Published
Abstract [en]

We present a method for fabricating highly conductive graphene-silver composite films with a tunable microstructure achieved by means of an inkjet printing process and low temperature annealing. This is implemented by starting from an aqueous ink formulation using a reactive silver solution mixed with graphene nanoplatelets (GNPs), followed by inkjet printing deposition and annealing at 100 degrees C for silver formation. Due to the hydrophilic surfaces and the aid of a polymer stabilizer in an aqueous solution, the GNPs are uniformly covered with a silver layer. Simply by adjusting the content of GNPs in the inks, highly conductive GNP/Ag composites (> 106 S m(-1)), with their microstructure changed from a large-area porous network to a compact film, is formed. In addition, the printed composite films show superior quality on a variety of unconventional substrates compared to its counterpart without GNPs. The availability of composite films paves the way to the metallization in different printed devices, e.g. interconnects in printed circuits and electrodes in energy storage devices.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
graphene, composite, inkjet printing
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-345709 (URN)10.1088/1361-6439/aaa450 (DOI)000423867400001 ()
Funder
Swedish Foundation for Strategic Research , Dnr SE13-0061Swedish Research Council, 621-2014-5596
Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2019-04-08Bibliographically approved
Song, M., Zhao, J., Grennberg, H. & Zhang, Z.-B. (2018). Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver. In: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac): . Paper presented at 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 12th – 14th June 2018, Oulu, Finland (pp. 35-39).
Open this publication in new window or tab >>Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver
2018 (English)In: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 2018, p. 35-39Conference paper, Published paper (Refereed)
Abstract [en]

This work provides a method to fabricate conductive composites by screen printing of aqueous hybrid inks with graphene oxide (GO) and silver acetate as silver source. The formulation of the aqueous hybrid inks is realized by mixing highly concentrated GO solution and reactive silver solution, which readily results in a formation of viscous pastes. Composite films with four-probe structure were fabricated by means of blade coating, followed by annealing at 160 °C in air and subsequently at 600 °C in Ar/H 2 . While the reactive silver solution without GO can be completely reduced when annealed at 90 °C in air, resulting in elemental Ag films with resistivity close to the bulk value, no reduction occurs in the hybrid inks under the same annealing condition. Silver nanoparticles are formed from the hybrid inks at 160 °C and discretely distributed on the reduced GOs (rGOs), which shows a retardation effect of GO on the reduction of silver. Further annealing at 600 °C in Ar/H 2 leads to partial restoration of sp 2 lattice in the rGOs. The resistivity of the composite films increases as the silver content is increased, which is interpreted by using a percolation model with rGO networks.

Keywords
annealing, coatings, electrical conductivity, electrical resistivity, graphene compounds, mixing, nanocomposites, nanofabrication, nanoparticles, percolation, reduction (chemical), silver, thin films, aqueous hybrid inks, silver acetate, reactive silver solution, silver nanoparticles, reduced graphene oxide, screen printed conductive composites, viscous pastes, four-probe structure, blade coating, retardation effect, percolation model, temperature 160.0 degC, temperature 600.0 degC, temperature 90.0 degC, CO-Ag, Ink, Films, Conductivity, Printing, Graphene, graphene oxide, conductive composite, screen printing
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-363974 (URN)10.23919/NORDPAC.2018.8423856 (DOI)
Conference
2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 12th – 14th June 2018, Oulu, Finland
Funder
Swedish Research Council, No. 621-2014-5596Swedish Foundation for Strategic Research , Dnr SE13-0061
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-03-14Bibliographically approved
Miao, F., Majee, S., Song, M., Zhao, J., Zhang, S. & Zhang, Z.-B. (2016). Inkjet printing of electrochemically-exfoliated graphene nano-platelets. Synthetic metals, 220, 318-322
Open this publication in new window or tab >>Inkjet printing of electrochemically-exfoliated graphene nano-platelets
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2016 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 220, p. 318-322Article in journal (Refereed) Published
Abstract [en]

In this study, we report on a facile method of inkjet printing of graphene nano-platelets (GNPs). The GNPs are exfoliated from graphite by means of an electrochemical process in an inorganic salt based electrolyte. The electrochemically exfoliated GNPs with oxygen-bearing functional groups exhibit spectroscopic features similar to those of reduced graphene oxides. As a result, ink formulation with such GNPs for inkjet printing readily accomplishes without using stabilizer and various conductive objects are easily fabricated on different substrates by inkjet printing. The as-printed films of the electrochemically exfoliated GNPs deliver an electrical conductivity of 44 S/m, a typical value for as-printed pristine GNP films in the literature. A simple thermal treatment results in an improved DC conductivity by two orders of magnitude to ~2.5 × 103 S/m.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Graphene; Electrochemical process; Inkjet printing
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-298103 (URN)10.1016/j.synthmet.2016.06.029 (DOI)000383811300040 ()
Funder
Swedish Foundation for Strategic Research , Dnr SE13-0061Swedish Research Council, 621-2014-5596
Available from: 2016-06-29 Created: 2016-06-29 Last updated: 2019-02-25Bibliographically approved
Majee, S., Song, M., Zhang, S.-L. & Zhang, Z.-B. (2016). Scalable inkjet printing of shear-exfoliated graphene transparent conductive films. Carbon, 102, 51-57
Open this publication in new window or tab >>Scalable inkjet printing of shear-exfoliated graphene transparent conductive films
2016 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 102, p. 51-57Article in journal (Refereed) Published
Abstract [en]

In this study, we demonstrate scalable and efficient inkjet printing of graphene flexible transparent conducting films (TCFs). The highly concentrated and stable graphene ink (3.2 mg/mL) that is dominated by 4-layer graphene flakes is achieved by means of shear exfoliation process. The printed graphene TCFs with DC conductivity of ∼4 × 104 S/m (sheet resistance 260 Ω/□ coupled with optical transparency of 86%) without intentional doping are readily obtained. Excellent flexibility and air stability of the printed graphene TCFs allow their potential applications in different flexible opto-electronics devices. Systematic investigation of the inkjet printing of graphene and the annealing effect on the graphene TCFs is presented.

Keywords
Graphene, Inkjet printing, Transparent conductive films
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-276479 (URN)10.1016/j.carbon.2016.02.013 (DOI)000372808200006 ()
Funder
Swedish Foundation for Strategic Research , Dnr SE13-0061Swedish Research Council, 621-2014-5596
Available from: 2016-02-14 Created: 2016-02-14 Last updated: 2019-02-25Bibliographically approved
Ahlberg, P., Hinnemo, M., Song, M., Gao, X., Olsson, J., Zhang, S.-L. & Zhang, Z.-B. (2015). A two-in-one process for reliable graphene transistors processed with photolithography. Applied Physics Letters, 107(20), Article ID 203104.
Open this publication in new window or tab >>A two-in-one process for reliable graphene transistors processed with photolithography
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2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 20, article id 203104Article in journal (Refereed) Published
Abstract [en]

Research on graphene field-effect transistors (GFETs) has mainly relied on devices fabricated using electron-beam lithography for pattern generation, a method that has known problems with polymer contaminants. GFETs fabricated via photo-lithography suffer even worse from other chemical contaminations, which may lead to strong unintentional doping of the graphene. In this letter, we report on a scalable fabrication process for reliable GFETs based on ordinary photo-lithography by eliminating the aforementioned issues. The key to making this GFET processing compatible with silicon technology lies in a two-in-one process where a gate dielectric is deposited by means of atomic layer deposition. During this deposition step, contaminants, likely unintentionally introduced during the graphene transfer and patterning, are effectively removed. The resulting GFETs exhibit current-voltage characteristics representative to that of intrinsic non-doped graphene. Fundamental aspects pertaining to the surface engineering employed in this work are investigated in the light of chemical analysis in combination with electrical characterization.

National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-269191 (URN)10.1063/1.4935985 (DOI)000365688700049 ()
Funder
Knut and Alice Wallenberg Foundation, 2011.0113, 2011.0082Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, 621-2014-5591
Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-12-01Bibliographically approved
Majee, S., Song, M., Zhang, S. L. & Zhang, Z. (2015). Production of transparent and conductive stable graphene ink for inkjet printing method. In: : . Paper presented at EMRS Fall Meeting 2015.
Open this publication in new window or tab >>Production of transparent and conductive stable graphene ink for inkjet printing method
2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Electrical interconnections are one of the main challenges in the printed electronics, to connect different functional units of an electronic device. With the progressive advancement of large area and low cost printed electronic devices on polymeric and paper substrates, the requirement for reliable interconnections with lower power consumption fabricated at low temperature is necessary. The conventional copper-based interconnections suffer severe problems in terms of cost efficiency when they are processed with photolithography technique. To replace the conventional metallic interconnections we have proposed printed interconnects with graphene inks. This is mainly motivated by two reasons. First, printing is a low-cost patterning approach which is performed at ordinary ambient condition. Printing of graphene proved to be a promising since it combines the attractive features of graphene and the cost effective printing methods (ink-jet printing, nozzle printing, spray printing) which enable additive patterning, direct writing, scalability to large area manufacturing. In order to facilitate the inkjet printing process, the graphene solution needs to be highly stable, uniform and should contain smaller sheet sizes (~ 1 micro meter) because of the limitation of the nozzle size of inkjet printing machine. In this work we have proposed a cost-effective approach for large-scale production of printable stable graphene suspension by liquid-phase shear exfoliation of graphite for printed electronics application. The process is scalable and requires shorter processing time compared to the other existing exfoliation methods. Graphene sheets have been exfoliated from graphite flakes in a solvent, cyclohexanone with ethyl cellulose as stabilizer. The graphene based solution prepared after several optimizations leads to a stable ink for more than six months without any sedimentation. The initial studies confirmed the production of graphene films with average sheet thickness of 10 to 20 nm and without any agglomeration with sheet sizes less than 1 micro meter. The rheological properties, such as, viscosity, of the produced graphene ink has been carefully tuned in order for successful inkjet printing process. Highly conductive and transparent (~70 % in the visible region) interconnections have been developed after several inkjet printing steps.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-260202 (URN)
Conference
EMRS Fall Meeting 2015
Available from: 2015-08-17 Created: 2015-08-17 Last updated: 2016-04-22
Song, M., Zhao, J., Riekehr, L., Grennberg, H. & Zhang, Z.-B.Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process.
Open this publication in new window or tab >>Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

We report an efficient one-step method to achieve highly reduced graphene oxide (rGO) hydrogel doped with nitrogen where the rGO sheets are interconnected forming a porous structure by means of hydrothermal process. During the synthesis, ammonium formate is used as reducing reagent and simultaneously as nitrogen supplier, which delivers nitrogen-doped rGO (NRGO) hydrogel that exhibits C/O atomic ratio as high as at ~11.1 and contains decent ~5.4 at.% nitrogen. As comparison, the reduction efficiency is only half of the value and no nitrogen doping can be obtained when L-ascorbic acid is used as reducing reagent. The resultant NRGO shows enhanced electrocatalytic ability for oxygen reduced reaction indicating its great potential of the one-step method for the catalyst and energy applications. 

Keywords
reduced graphene oxide, ammonium formate, hydrothermal, reduction, oxygen reduction reaction
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-377624 (URN)
Funder
Swedish Foundation for Strategic Research , Dnr SE13-0061Swedish Research Council, 621-2014-5596
Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2019-02-25
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