Improving Printability of Functional Materials by. Laboratory of Paper Coating and Converting Martti Toivakka and Jouko Peltonen

Transcription

1 Improving Printability of Functional Materials by Controlled Substrate Topography and Chemistry Laboratory of Paper Coating and Converting Martti Toivakka and Jouko Peltonen

2 Printed functionality & Paper electronics We want mass-produced, inexpensive, environmentally sound concepts Throw-away electronics Traditionally produced on plastics: + Smooth, chemically inert Limited possibilities to adjust printability Paper and board usually not considered as options: Porous, rough, poor dimensional stability + A number of possibilities to adjust the printability + Environmentally friendly + Cost-competitivity, availability

3 What does printability mean? For traditional graphic printed products defined as a combination of: Runnability of the press (e.g., lack of webbreaks, accumulation problems, fold-cracking, blistering etc.) Adequate print (product) quality (e.g., color reproduction, uniformity of print, print gloss, missing dots, print through etc.) For printed functional devices: Not well-defined currently Determined mostly by the printed device to be produced

4 Improving printability of functional materials Printability determined by compatibility of ink substrate printing method We need to measure and control surface properties: roughness, porosity, wettability, chemical activity/inertness, barrier properties, mechanical properties Surface treatment methods to improve printability: Existing: surface sizing pigment coating dispersion coating extrusion coating corona Novel methods: plasma activation plasma coating nanoparticle deposition sol-gel coating chemical vapor deposition

5 Control of wetting with LFS (Liquid Flame Spray) Water contact angle TiOx Reference SiOx Petal Effect (Cassie impregnating wetting regime) TAMPERE UNIVERSITY OF TECHNOLOGY M. Stepien, J. J. Saarinen, H. Teisala, M. Tuominen, M. Aromaa, J. Kuusipalo, J. M. Mäkelä, and M. Toivakka, ADJUSTABLE WETTABILITY OF PAPERBOARD BY LIQUID FLAME SPRAY PROCESS, submitted to Applied Surface Science, 2010.

6 Example substrate concept for paper electronics Topcoating (Kaolin) 0.5-5µm Barrier layer (Latex) 1-10 µm Smoothing layer (Kaolin) Precoating (GCC) Basepaper R. Bollstrom, A. Määttänen, P. Ihalainen, J. Peltonen, M. Toivakka,: Org. Electronics, 10, 1020 (2009) R. Bollström, A. Määttänen, P. Ihalainen, M. Toivakka, J. Peltonen: Patent application PCT/FI2010/050056

7 Barrier properties and solvent resistance Topside Backside Acetone Toluene IPA CB DCB THF DMSO DMF Xylene Acetic acid HCL NaOH Drop size 5µl Precoating Smoothing layer Barrier layer 10 mm P3HT in DCB Topcoating PCC Kaolin Mylar A R. Bollstrom, A. Määttänen, P. Ihalainen, J. Peltonen, M. Toivakka,: Org. Electronics, 10, 1020 (2009)

8 Adjusting the printability by top coating formulation Printability of Ag ink 100pph PCC 10pph SB latex Coating thickness 3µm 100pph kaolin 10pph SB latex Coating thickness 3µm 70pph kaolin 30pph PCC 4pph SB latex Coating thickness 6µm Surface energy ~30mN/m Medium pore volume Surface energy ~40mN/m Low pore volume Surface energy ~40mN/m High pore volume R. Bollström et.al, unpublished, 2010.

9 Control of surface roughness Calendered topcoating (Kaolin) RMS 55 nm Barrier layer (Latex) RMS 260 nm Smoothing layer (Kaolin) RMS 300 nm Precoating (GCC) RMS 580 nm Washed Mylar A RMS 30 nm Top coating: improves the printability, the amount of functional inks can be adjusted by the thickness, porosity and surface energy of this layer. J. Järnström, P. Ihalainen, K. Backfolk, J. Peltonen: Applied Surface Science 2542 (2008) 5741 R. Bollstrom, A. Määttänen, P. Ihalainen, J. Peltonen, M. Toivakka,: Org. Electronics, 10, 1020 (2009) R. Bollström, A. Määttänen, P. Ihalainen, M. Toivakka, J. Peltonen: Patent application PCT/FI2010/050056

10 Analysis of surface roughness Topcoating Barrier layer Smoothing layer Precoating Basepaper AFM and COM data Micro-and macroscale roughness relevant for flexo, offsett, etc. and for conventional printing quality. Inkjet-printed polyaniline Nano-and microscale roughness most relevant for inkjet printing and for functionality. J. Järnström, P. Ihalainen, K. Backfolk, J. Peltonen: Applied Surface Science 2542 (2008) 5741 J. Järnström, P. Ihalainen, A. Lemström, M. Toivakka, J. Peltonen: NPPRJ 24 (2009) 327. J. Järnström: PhD thesis,2010.

11 Mapping of surface mechanics and chemistry Kaolin-SB latex coated paper (2.5 x 2.5 µm 2 ) Topograph Z-scale: 600 nm Elastic modulus map -Z-scale: 5 GPa -light high modulus Adhesion map -Z-scale: 30 nn -dark low adhesion Torsional harmonic AFM enables mapping of local material properties. Local mechanical properties influence print quality of e.g. rotogravure printing. Local chemical properties important especially for inkjet, compare for Cassie surfaces. P. Ihalainen, J. Järnström, A. Määttänen, J. Peltonen: Colloids Surfaces A, submitted

12 Inkjet printability through control of wettability Inkjet droplet: 0.5 wt.% P3HT in o-diclorobenzene, V = 10 pl σ LW [mn/m] PET R = 0.97 Kaolin C P3HT 35 Kaolin B PCCA Surfaceenergyof topcoatingcanbe adjusted not possible for PET! PCC B Kaolin A Barrier diameter (Inkjet droplet) [µm] Topcoating Barrier layer Smoothing layer Precoating 12 Basepaper A. Määttänen, P. Ihalainen, M. Toivakka, R. Bollström, J. Peltonen: Colloids Surfaces A, submitted.

13 Examples of demonstrators Printed transistor (HIFET) Printable ph sensor based on PANI Electropolymerization on paper Electrochemical actuation of liquids on paper

14 Printed Hygroscopic Insulator FET (HIFET) Solvent: ethanol, ethandiol and water Solvent: water or ethanol Solvent: etylacetate, IPA, hexanol and water Solvent: DCB, CB, xylene, toluene and chloroform I-V Characteristics Spincoated transistor on paper Immediately after manufacturing After 4,5 months of storage in room atmosphere Inkjet printed transistor on paper

15 Printable ph sensor based on PANI Ag electrodes R Liquid cell ph = 4, 7, or 10 PANI Multilayer coated paper R

16 Electropolymerization on paper Formation of PEDOT-Cl film by galvanostatic electropolymerization PANI Ag WE=PANI RE=Ag /AgCl CE=Pt PEDOT-Cl EDOT + KCl PEDOT-Cl A. Määttänen, M. Stepien, P. Ihalainen, M. Toivakka, U. Mattinen, J. Bobacka, J. Peltonen: Thin Solid Films, submitted.

17 Electrochemical actuation of liquids on paper J.J. Saarinen, A. Määttänen, R. Bollström, P. Ihalainen, J. Peltonen: Appl. Surf. Sci., submitted. J. J. Saarinen et al., TAPPI International Conference on Nanotechnology for the Forest Products Industry, Edmonton, Canada, 2009.

18 Summary While having some short-comings as a substrate, paper and board have a few advantages over plastic substrates: Better control of surface energy and wetting Allows for online sintering of metal inks with infrared radiation Environmentally friendly, compostable, widely available We have gained improved understanding of what is required from the substrate for printability and for a given device A number of functional device concepts produced by printing on paper have been demonstrated Roll-to-roll fabrication of a transistor demonstrated, up-scaling considered

19 Thank you for your attention!