INFINITY Consortium: Development of Indium-Free Transparent Conductive Films by the Sol-Gel Method M. Skof 1,2 , H. Wang 2 , A. Walker 1 , A. Rana 1 , A. Rexach 1 1 TWI Ltd., UK, 2 Materials & Engineering Research Institute, Sheffield Hallam University, UK This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 641927. Information is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and liability. © 2016 INFINITY. All rights reserved. Captions Captions Motivation The Project o Problem: increasing demand for indium tin oxide (ITO), decreasing resources, high price [1, 2] o Aim: finding an alternative to ITO as standard for transparent conductive coatings (TCCs) , f.e. for displays and solar cells o Approach: low cost sol-gel process, using widely available metallic elements and recent advantages in nanostructured coatings o Potential ITO Substitute: Titanium dioxide based material, doped o Desired outcome: process route to fabricate a printable ink and low temperature sintering process for conductive coatings on glass and plastic substrates Conclusion and Future Work Summary o Interference colours suggest that coating was formed o XRD patterns showed formation of desired TiO 2 anatase structure for sintering temperatures above 600°C o SEM micrographs indicate porous coating with embedded nanoparticles Next Steps o Vary reaction conditions • pH, solvent, precursor, water o Define degree of cross linking in solution and coating o Optimise drying/curing step (temperature, atmosphere) o Determine conductivity of coatings o Change doping levels Sol-Gel Process The Chemistry Acknowledgments Thank you to… o European Commission, EASME, Horizon 2020 o Alec Gunner, Alan Taylor TWI Ltd. o Anthony Bell, Sheffield Hallam University o Simon Rushworth, EpiValence Contact: [email protected] For more information visit: www.infinity-h2020.eu Results Coated Glass Slides o Coated glass slides show interference colours o Colours correlate with concentration of precursor (further studies needed) XRD-Analysis o Sintering at temperatures below 600°C yields amorphous structure (left), above 600°C TiO 2 -anatase peak forms Microstructure o Multi-coating process leads to surface defects o Coating is very porous, connectivity needs to be improved o Nanoparticles are clearly visible (Figure 9 on right side) Figure 1: Three main reactions in sol-gel process [3] (X, Y, Z) = M(OR) x (OH) y (OM) z X + Y + Z = 4 Figure 2: Hydrolysis/condensation steps in matrix form [3] o Structure of products depends on reaction rates • Influenced by nature and concentration of metal, catalyst, solvent as well as temperature and pH value of solutions o Aim: Formation of a crosslinked polymeric network Figure 3: Network (schematic) References [1] C. Jariwala et.al, Preparation and Characterization of Antimony Doped Tin Oxide Thin Films Synthesized by Co-Evaporation of Sn and Sb using Plasma Assisted Thermal Evaporation, Journal of Nano- and Electronic Physics, vol. 5, no. 2, pp. 1-5, 2015. [2] Y. Furubayashi et.al, Novel transparent conducting oxide: Anatase Ti1−xNbxO2, Thin Solid Films, vol. 496, no. 1, pp. 157-159, 2006. [3] C. Brinker, G. Scherer, Sol-Gel Science. Boston: Academic Press, 1990. Figure 10: Hydrolysed (left) vs. clear sample Figure 4: Coated glass slides, precursor concentrations T47: low - T50: high Figure 5: XRD of T50 samples sintered at 400°C and 500°C for 25 min, measurement over 1 hour, 20-70 degrees 2theta. 296 264 0 50 100 150 200 250 300 350 20 30 40 50 60 70 Counts Position °2 Theta XRD – Controlling of Sintering 700°C 600°C 0 50 100 150 200 250 300 20 30 40 50 60 70 Counts Position °2 Theta XRD – Controlling of Sintering 500°C 400°C Figure 6: XRD of T50 samples sintered at 600°C and 700°C for 25 min, measurement over 1 hour, 20-70 degrees 2theta Figure 7-9: Micrographs showing overview of multi-coated slide on the left, microstructure of surface in the middle and close-up with nanoparticles visible on the right 7 8 9 T47 blank T50 T49 T48