1. Advances in Electroluminescent Devices with Barium Titanate Particles
By Antoine Dumont, Sylvie morin
CAP Congress 2017, Queen’s University

2. Objectives
Synthesis of BaTiO3 nanoparticles of a controlled size and structure for an electric permittivity study in an electroluminescent device (ELD). (Professor Sylvie Morin, collaboration with W. J. Pietro, York University)
Analysis of the effect of lanthanum doping in barium titanate and optimization of the concentration for our application.

3. Presentation Overview
Barium titanate particles - Synthesis - Characterization
Electroluminescent devices - Experimental techniques - Permittivity and Luminescence results

4. Barium Titanate
BaTiO3 has applications in multilayer ceramic capacitors, infrared detectors and thermistors
Lattice structure 1 Ba (apex of lattice)
1 Ti (center of lattice)
3 O (face-centered)
High dielectric materials are of great interest for developments in nanotechnology.

5. Barium Titanate c c a c a a
Proposed core-shell structure for particles of around 100nm a c
Tetragonal
Cubic a c a c
Smaller Particles
Bigger Particles
Aoyagi S. et al, JTAC, 81 (2005) Wada S. et al, Journal of App. Physics, 42 (2003)

6. Particles Synthesis : Sol-Gel Method
Process : - Bonding of metal with organic precursor M(OR)n - Hydrolysis by adding water solution M(OH)n - Condensation by adding base MOn - Thermal treatment
Advantages : control of size & low temperature
Strong bonds M-O-M-O-(...), only break above 1000°C
Samples created with 0.0, 0.3, 0.5 and 0.7mol% lanthanum concentration

7. Characterization of Particles
SEM images
Experimental particles Commercial powder
100 nm
400 nm
1 μm

8. Characterization of Particles
X-ray diffraction
Identification of BaTiO3 crystal structure Rietveld analysis: Peaks between tetragonal and cubic
Possible core-shell structure suggested in literature

9. Characterization of Particles
Induced coupled Plasma Atomic Emission Spectroscopy
0.3%La %La %La

10. Electroluminescent Device Design
19mm
Bottom view
20mm
19mm
ZnS
BaTiO3 Ag
Top view
Silver
Silver
Silver
BaTiO3
2mm
ZnS
ITO coated Plastic Conductive Non-conductive

11. Electroluminescent Device Support

12. Electroluminescent Device
Whole device 0.3 mm thick, including plastic. All layers are inks (epoxy, particles, solidifier)

13. Impedance Analysis Impedance Spectroscopy
Studying the system’s behaviour (Leaking Resistance, Capacitance) with a varying current
Nyquist Plot : Imaginary part of impedance Z as a function of the real part. Equivalent circuit for our devices : And the circuit’s impedance :

14. Impedance Analysis Impedance measured from 500Hz to 10 000Hz
Blue : Exp. Data
Red : Sim. Data

15. Electroluminescent Device Result
0.5% La doped BaTiO3 material showed a minimum of 20% superior permittivity compared to all our other samples, expected behavior*
BatiO3 Sample with 0.5% La doping showed extraordinary emission of light
- Anomaly among other samples but is a real result
- Leaking resistance 32% lower than similar devices!
Com % La %La %La %La
* Vijatovic Petrovic M.M. et al, Mat. Char., 62 (2011) Beltran H. et al, J. Am. Ceram. Soc., 87 (2005)

16. Electroluminescent Device Result
New BaTiO3 synthesis to try to reproduce the result… without success (14 new samples)
Confirmation of 0.5% La concentration superiority over the next best (0.7%)
0.5% La % La

17. Electroluminescence Efficiency
Trend among samples : ELD’s efficiency seems to have a reverse proportionality with the leaking resistance of the dielectric, after a threshold limit.
I∝ 1 𝑅 ???
Not a typical focus for advances in this field but could introduce a new way to improve the energy efficiency.

18. Conclusion
Significant improvement of luminescence for BaTiO3 based electroluminescent devices
Possible colossal increase of luminescence under the right leaking resistance conditions
Upcoming work :
Collaboration for use of industrial printer for precise thickness and resistance-controlled device fabrication

19. Acknowledgment
Support and collaboration with colleagues in Sylvie Morin’s group
Funding :

20. Screen-printing apparatus