| 1. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Photodetector of multilayer exfoliated MoS2 deposited on polyimide films
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We fabricated a photodetector based on multilayer molybdenum disulfide (MoS2) by micromechanical cleavage of a molybdenite crystal using a polyimide film. We deposited 40 nm of gold by vacuum sputtering and copper tape was used for the contacts. Without any surface treatment, we achieved high responsivity at different incident optical power. The calculated responsivity was 23 mA/W of incident optical power in the range between 400 and 800 nm. For the responsivity measurement it was estimated that MoS2 have a bandgap of 1.6 eV, which lies between monolayer and multilayer films. The thickness of the MoS2 thin film was determined by Raman spectroscopy evaluating the difference between the in plane and out of plane Raman modes. The measurement of IV curves indicated Ohmic contacts in respect to the Au regardless of the incident optical power. Our device fabrication was much simpler than previous reported devices and can be used to test the light absorption and luminescence capabilities of exfoliated MoS2.
|
|
| 2. |
- Alecrim, Viviane, et al.
(författare)
-
Exfoliated Layered Materials for Digital Fabrication
- 2015
-
Ingår i: NIP & Digital Fabrication Conference. ; , s. 192-194
-
Konferensbidrag (refereegranskat)abstract
- We introduced an exfoliation method of MoS2 in a 3% solution of sodium dodecyl surfactant at high concentration (i.e. 2 g/L). The bulk MoS2 was thinned by mechanical exfoliation between sand papers and the resulting powder was used to prepare dispersions by liquid exfoliation through probe sonication. The resulting dispersion consisted of very thin MoS2 nanosheets in surfactant solution with average lateral size around 126 nm. This may be interesting for applications in inkjet printed electronics.
|
|
| 3. |
- Andersson, Henrik, et al.
(författare)
-
Assembling surface mounted components on ink-jet printed double sided paper circuit board
- 2014
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:9
-
Tidskriftsartikel (refereegranskat)abstract
- Printed electronics is a rapidly developing field where many components can already be manufactured on flexible substrates by printing or by other high speed manufacturing methods. However, the functionality of even the most inexpensive microcontroller or other integrated circuit is, at the present time and for the foreseeable future, out of reach by means of fully printed components. Therefore, it is of interest to investigate hybrid printed electronics, where regular electrical components are mounted on flexible substrates to achieve high functionality at a low cost. Moreover, the use of paper as a substrate for printed electronics is of growing interest because it is an environmentally friendly and renewable material and is, additionally, the main material used for many packages in which electronics functionalities could be integrated. One of the challenges for such hybrid printed electronics is the mounting of the components and the interconnection between layers on flexible substrates with printed conductive tracks that should provide as low a resistance as possible while still being able to be used in a high speed manufacturing process. In this article, several conductive adhesives are evaluated as well as soldering for mounting surface mounted components on a paper circuit board with ink-jet printed tracks and, in addition, a double sided Arduino compatible circuit board is manufactured and programmed.
|
|
| 4. |
- Balliu, Enkeleda, et al.
(författare)
-
Laser sintering of silver nano-particles inks printed on paper substrates
- 2015
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 9781628414417 ; , s. Art. no. 935112-
-
Konferensbidrag (refereegranskat)abstract
- In this work we have investigated the use of laser sintering of different ink-jet printed nano-particle inks (NPIs) on paper substrates. Laser sintering is shown to offer a fast and non-destructive way to produce paper based printed electronics. A continuous wave fiber laser source at 1064 nm is used and evaluated in combination with a galvo-scanning mirror system. A conductivity in order of 2.16 ∗ 107 S/m is reached for the silver NPI structures corresponding to nearly 35 % conductivity compared to that of bulk silver and this is achieved without any observable damage to the paper substrate. © 2015 SPIE.
|
|
| 5. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Exfoliated MoS2 in Water without Additives
- 2016
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants andother funtionalization agents. Pure water should be an ideal solvent, however, it is generallybelieved, based on solubility theories that stable dispersions of water could not be achievedand systematic studies are lacking. Here we describe the use of water as a solvent and thestabilization process involved therein. We introduce an exfoliation method of molybdenumdisulfide (MoS2) in pure water at high concentration (i.e., 0.14±0.01 g L−1). This was achieved by thinning the bulk MoS2by mechanical exfoliation between sand papers and dis-persing it by liquid exfoliation through probe sonication in water. We observed thin MoS2nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of thenanosheets were around 200 nm, the same range obtained in organic solvents. Electropho-retic mobility measurements indicated that electrical charges may be responsible for the sta-bilization of the dispersions. A probability decay equation was proposed to compare thestability of these dispersions with the ones reported in the literature. Water can be used as asolvent to disperse nanosheets and although the stability of the dispersions may not be ashigh as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable.
|
|
| 6. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Printability of functional inkjet inks onto commercial inkjet substrates and a taylor made pigmented coated paper
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Printed electronics are of increasing interest. The substrates used have primarily been plastics although the interest for cellulose-based substrates is increasing due to the environmental aspect as well as cost. The requirements of substrates for electronically active inks differs from graphical inks and therefore we have investigated a custom-made pigment based coated paper and compared it to commercial photo-papers and a coated PE film.Our goal with the study of different substrates was to select the most suitable substrate to print water based 2D materials inkjet inks for flexible electronics.The discovery of graphene, a layered material achieved from the exfoliation of graphite, has resulted in the study of other materials with similar properties to cover areas where graphene could not be used due to the absence of a bandgap in the material. For example in thin film transistors (TFT) a semiconductor layer is essential to enable turn on and off the device. This semiconductor layer can be achieved using various materials but particular interest have been dedicated to abundant and cheap 2D materials such as the transition metal dichalcogenide (TMD) molybdenum disulfide (MoS2). To date, most of the dispersions based on TMDs use organic solvents or water solutions of surfactants. Previously we focus on the study of environmental friendly inks produced by liquid phase exfoliation (LPE) of MoS2 in water using cellulose stabilizers such as ethyl cellulose (EC), cellulose nanofibrils (CNF) and nanofibrilcellulose (NFC). We have study various aspects of the ink fabrication includi ng pH range, the source of MoS2, nanosheets thickness, particle size distribution, ink stabilizers, ink concentration, viscosity and surface tension. These inks have very low concentration requiring a number of printing passes to cover the substrate. Therefore the substrate selection is crucial as a large amount of solvent is to be absorb by the substrate. Our goal was to use such an ink to print electrodes of MoS2 into a paper substrate after substrate selection.Commercial photo papers, a commercial coated PE film and a tailor made multilayer pigment coated paper substrate were used for the substrate selection analysis. We print the substrates using a DIMATIX inkjet printer with a 10 pL printing head using the distillated water waveform supplied by the printer manufacturer. The voltage used was 23V and 4 nozzles were used for the print outs. The inkjet ink used was the organic PEDOT:PSS. We printed lines ranging from 1 pixel to 20 pixels with 1, 2 and 3 printing passes. The printing quality was evaluated through measurements of the waviness of the printed lines measured after imaging the printed samples with a SEM microscope. The line width measurement was done using the software from the SEM.We also evaluated the structure of the coatings using SEM and topography measurements. The ink penetration through the substrates was evaluated using Raman Spectroscopy. For the pigmented coated sample we measured 4% of ink penetration through the substrate for the 1pxl printed line printed once onto the paper. Cross-section SEM images of the printed lines were made to visualize the ink penetration into the substrate.Regarding the electrical conductivity of the printed samples, the differences in resistivity varying the width of the printed lines and the number of printed passes were evaluated. The resistivity of the printed electrodes was evaluated using the 2-points probe method. Before the resistivity measurements, the printed substrates were heated at 50°C and 100°C for 30 minutes in an oven.We choose the PEDOT:PSS ink because it is a low price ink compared to metal nanoparticles inks for printed electronics. The print outs had low resistivity at a few printing passes with no need for sintering at high temperatures. The MoS2 ink has a very high resistance at a few printing passes due to lower coverage of the substrate therefore for this ink these measurements were not possible to be made. The main pigment composition of the paper coatings of the substrates was evaluated using FT-IR and EDX, these data plus the coating structure evaluated by SEM was related to the print quality.The best in test papers were used to print MoS2 electrodes. After the printing tests, another step for the optimization of the MoS2 ink properties shall be carried out in future studies for better print quality. We also evaluated the surface energy of the substrates through contact angle measurements to match the surface tension of the PEDOT:PSS ink and later the MoS2 ink. Although the pigmented coated printing substrate did not show better results than the commercial photo papers and PE foil in terms of line quality, it shows the lowest resistivity and sufficient results for low cost recyclable electronics, which do not require high conductivity. Nevertheless, the substrate was very thin and it could even be used in magazines as traditional lightweight coated papers (LWC) are used but with the additional of a printed electronic feature.
|
|
| 7. |
- Zhang, Renyun, et al.
(författare)
-
Cellulose-Based Fully Green Triboelectric Nanogenerators with Output Power Density of 300 W m−2
- 2020
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 32:38
-
Tidskriftsartikel (refereegranskat)abstract
- Triboelectric nanogenerators (TENGs) have attracted increasing attention because of their excellent energy conversion efficiency, the diverse choice of materials, and their broad applications in energy harvesting devices and self-powered sensors. New materials have been explored, including green materials, but their performances have not yet reached the level of that for fluoropolymers. Here, a high-performance, fully green TENG (FG-TENG) using cellulose-based tribolayers is reported. It is shown that the FG-TENG has an output power density of above 300 W m−2, which is a new record for green-material-based TENGs. The high performance of the FG-TENG is due to the high positive charge density of the regenerated cellulose. The FG-TENG is stable after more than 30 000 cycles of operations in humidity of 30%–84%. This work demonstrates that high-performance TENGs can be made using natural green materials for a broad range of applications.
|
|
| 8. |
- Zhang, Renyun, et al.
(författare)
-
Energy Harvesting Using Wastepaper-Based Triboelectric Nanogenerators
- 2023
-
Ingår i: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 25:11
-
Tidskriftsartikel (refereegranskat)abstract
- Inks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. Herein, high-output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) are reported. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W m−2, which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper. The maximum open circuit voltage (V OC) and short circuit current (I SC) are 774 V and 3.92 mA (784 mA m−2), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.
|
|
| 9. |
- Zhang, Renyun, et al.
(författare)
-
High-performance transparent and flexible electrodes made by flash-light sintering of gold nanoparticles
- 2018
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:12, s. 7191-7198
-
Tidskriftsartikel (refereegranskat)abstract
- Metallic nanowire-based transparent electrodes (TEs) are potential alternatives to indium tin oxide (ITO). To achieve a high performance [sheet resistance (Rs) < 100 Ω/sq, transmittance (T%) > 90%], the nanowires must have a high length-to-diameter (L/D) ratio to minimize the number of wire-to-wire junctions. Attempts to produce TEs with gold nanowires have been made, and the results reveal difficulties in achieving the requirements. A successful strategy involves creating templated gold nanonetworks through multiple procedures. Here, we present a simple and efficient method that uses flash-light sintering of a gold nanonetwork film into gold TEs (Rs: 82.9 Ω/sq, T %: 91.79%) on a thin polycarbonate film (25 μm). The produced gold TEs have excellent mechanical, electrical, optical, and chemical stabilities. Mechanisms of the formation of gold nanonetworks and the effect of flash-light have been analyzed. Our findings provide a scalable process for producing transparent and flexible gold electrodes with a total processing time of less than 8 min without the use of heating, vacuum processing, and organic chemicals and without any material loss. This is possible because all the gold nanoparticles have been aggregated and filtrated on the filter membranes. The area density of gold is 0.094 g/m2 leading low material costs, which is very competitive with the price of commercial TEs.
|
|
| 10. |
- Zhang, Renyun, et al.
(författare)
-
Photoconductivity of acid exfoliated and flash-light-processed MoS2 films
- 2018
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- MoS2 has been studied intensively during recent years as a semiconducting material in several fields, including optoelectronics, for applications such as solar cells and phototransistors. The photoresponse mechanisms of MoS2 have been discussed but are not fully understood, especially the phenomenon in which the photocurrent slowly increases. Here, we report on a study of the photoresponse flash-light-processed MoS2 films of different thicknesses and areas. The photoresponse of such films under different light intensities and bias voltages was measured, showing significant current changes with a quick response followed by a slow one upon exposure to pulsed light. Our in-depth study suggested that the slow response was due to the photothermal effect that heats the MoS2; this hypothesis was supported by the resistivity change at different temperatures. The results obtained from MoS2 films with various thicknesses indicated that the minority-carrier diffusion length was 1.36 mu m. This study explained the mechanism of the slow response of the MoS2 film and determined the effective thickness of MoS2 for a photoresponse to occur. The method used here for fabricating MoS2 films could be used for fabricating optoelectronic devices due to its simplicity.
|
|
