INFINITY Consortium:

Development of Indium-Free Transparent Conductive Films by the Sol-Gel Method

M. Skof1,2 , H. Wang2, A. Walker1, A. Rana1, A. Rexach1

1TWI Ltd., UK, 2Materials & Engineering Research Institute, Sheffield Hallam University, UK

T h i s p r o j e c t h a s r e c e i v e d f u n d i n g f r o m t h e E u r o p e a n U n i o n ’ s H o r i z o n 2 0 2 0 r e s e a r c h a n d i n n o v a t i o n p r o g r a m m e u n d e r g r a n t a g r e e m e n t N o 6 4 1 9 2 7 . I n f o r m a t i o n i s p r o v i d e d

a s i s a n d n o g u a r a n t e e o r w a r r a n t y i s g i v e n t h a t t h e i n f o r m a t i o n i s f i t f o r a n y p a r t i c u l a r p u r p o s e . T h e u s e r t h e r e o f u s e s t h e i n f o r m a t i o n a t i t s s o l e r i s k a n d l i a b i l i t y .

© 2 0 1 6 I N F I N I T Y . A l l r i g h t s r e s e r v e d .

Captions

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MotivationThe 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 WorkSummary

o Interference colours suggest that coating was formed

o XRD patterns showed formation of desired TiO2 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 ProcessThe Chemistry

AcknowledgmentsThank 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: mirjam.skof@nsirc.co.ukFor more information visit: www.infinity-h2020.eu

ResultsCoated 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 TiO2-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 networkFigure 3: Network

(schematic)

References

[1] C. Jariwala et.al, Preparation and Characterization of Antimony DopedTin Oxide Thin Films Synthesized by Co-Evaporation of Sn and Sb usingPlasma Assisted Thermal Evaporation, Journal of Nano- and ElectronicPhysics, vol. 5, no. 2, pp. 1-5, 2015.

[2] Y. Furubayashi et.al, Novel transparent conducting oxide: AnataseTi1−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.

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Position °2 Theta

XRD – Controlling of Sintering

700°C

600°C

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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

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T47 blankT50T49T48