Structural evolutions in electroactive poly(vdf-co-trfe) copolymers for organic electronics

Transcription

1 10/03/16 New-Orleans-USA Structural evolutions in electroactive poly(vdf-co-tr) copolymers for organic electronics François Bargain, Sylvie Tencé-Girault, Fabrice Domingues Dos Santos, Michel Cloitre Soft Matter and Chemistry Laboratory 1

2 PVDF-based semi-crystalline polymers 2/16 H F H F VDF PVDF

3 PVDF-based semi-crystalline polymers 2/16 H F H F VDF PVDF TGTG α phase Stretching TTTT β phase

4 PVDF-based semi-crystalline polymers 2/16 H F H F VDF PVDF TGTG α phase Stretching TTTT β phase H F H F VDF + F F H F Tr P(VDF-co-Tr)

5 PVDF-based semi-crystalline polymers 2/16 H F H F VDF H F H F VDF + F F H F Tr PVDF P(VDF-co-Tr) α phase b TGTG c Stretching Ferroelectric () Phase TTTT β phase μ

6 PVDF-based semi-crystalline polymers 2/16 H F H F H F H F VDF + F F H F VDF Tr Polarization displacement PVDF P(VDF-co-Tr) Ferroelectricity P r = 60 mc/m 2 E c = 50 V/µm Piezoelectricity d 33 = - 20 pc/n α phase b TGTG c Stretching Ferroelectric () Phase TTTT β phase μ

7 PVDF-based semi-crystalline polymers 2/16 H F H F H F H F VDF + F F H F VDF Tr Polarization displacement PVDF P(VDF-co-Tr) Ferroelectricity P r = 60 mc/m 2 E c = 50 V/µm Piezoelectricity d 33 = - 20 pc/n α phase b TGTG c Stretching Ferroelectric () Phase Curie Transition Paraelectric (PE) Phase TTTT β phase μ

8 Applications in printed organic electronics 3/16 Manufacturing thin, light and flexible devices using ink-jet printing, press-printing Sensors keyboards Ferroelectric memories Direct piezoelectric smart labels Ferroelectric Inverse piezoelectric Actuators speakers

9 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase 80 25

10 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase Spreading

11 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase Spreading 2 Evaporation

12 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase Spreading 2 Evaporation 3 Annealing

13 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase Spreading 2 Evaporation 3 Annealing 4 Poling E = 150 V/µm E

14 From polymer solution to electroactive film 4/16 Melt T Melting Paraelectric (PE) Phase 130 T ( C) T Curie Ferroelectric () Phase Applications 1 Spreading 2 Evaporation 3 Annealing 4 Poling E = 150 V/µm E

15 Motivations for organic electronics 5/16 Lot of studies have been done on annealed and stretched films obtained from solvent or from the melt. An intermediate phase with a tilt has also been observed for VDF mol % CL PE Tashiro et al, Polymer, 1986

16 Motivations for organic electronics 5/16 Lot of studies have been done on annealed and stretched films obtained from solvent or from the melt. An intermediate phase with a tilt has also been observed for VDF mol % CL PE Our work focuses specifically on isotropic solvent-cast samples to be close to printed organic electronics applications Tashiro et al, Polymer, 1986

17 Motivations for organic electronics 5/16 Lot of studies have been done on annealed and stretched films obtained from solvent or from the melt. An intermediate phase with a tilt has also been observed for VDF mol % CL PE Our work focuses specifically on isotropic solvent-cast samples to be close to printed organic electronics applications Tashiro et al, Polymer, 1986 Understanding the crystalline and morphological changes upon annealing and poling steps

18 Morphology and crystalline organization 6/ m 10 nm nm Spherulites SEM Crystalline lamellae SAXS Crystalline cell WAXS 5 µm L P = 2π/q 2d hkl sinθ = λ Spherulite size Long period L P Electronic contrast Inter-planar distances d hkl Crystallinity χ c

19 Morphology and crystalline organization 6/ m 10 nm nm Spherulites SEM Crystalline lamellae SAXS Crystalline cell WAXS 5 µm L P = 2π/q 2d hkl sinθ = λ Spherulite size Long period L P Electronic contrast Inter-planar distances d hkl Crystallinity χ c

20 Morphology and crystalline organization 6/ m 10 nm nm Spherulites SEM Crystalline lamellae SAXS Crystalline cell WAXS 5 µm L P = 2π/q 2d hkl sinθ = λ Spherulite size Long period L P Electronic contrast Inter-planar distances d hkl Crystallinity χ c

21 Simultaneous SAXS-WAXS experiments 7/16 Collaboration with: Pierre Panine Grenoble, FRANCE Solvent-cast samples of 20 µm thickness poly(vdf-co-tr) 70/30 mol %

22 Simultaneous SAXS-WAXS experiments 7/16 Collaboration with: Pierre Panine Grenoble, FRANCE Solvent-cast samples of 20 µm thickness poly(vdf-co-tr) 70/30 mol %

23 Simultaneous SAXS-WAXS experiments 7/16 Collaboration with: Pierre Panine Grenoble, FRANCE Solvent-cast samples of 20 µm thickness poly(vdf-co-tr) 70/30 mol % hot stage 130 T( C) 1 C/min 25 Time

24 Simultaneous SAXS-WAXS experiments 7/16 Collaboration with: Pierre Panine Grenoble, FRANCE Solvent-cast samples of 20 µm thickness poly(vdf-co-tr) 70/30 mol % D SAXS 1-2 m hot stage T( C) 1 C/min Time D WAXS 10 cm Simultaneous acquisition 1 SAXS and 1 WAXS image /min

25 SAXS on solvent-cast sample 8/16 T( C) Heating ANNEALING 10 min Cooling q (nm -1 )

26 SAXS on solvent-cast sample 8/16 L P = 15 nm T( C) Heating L P = 38 nm ANNEALING 10 min L P = 30 nm Cooling q (nm -1 )

27 SAXS on solvent-cast sample 8/16 L P = 15 nm T( C) Heating L P = 38 nm ANNEALING 10 min L P = 30 nm Cooling q (nm -1 ) Increase of the long period from 15 nm to 30 nm

28 WAXS on solvent-cast sample 9/16 T( C) Heating ANNEALING 10 min Cooling

29 WAXS on solvent-cast sample 9/16 Phase T( C) Orthorhombic symmetry Heating PE Phase Hexagonal symmetry Cooling PE ANNEALING 10 min PE T C + D T C D

30 WAXS on solvent-cast sample 9/16 Phase T( C) Orthorhombic symmetry Heating PE Phase Hexagonal symmetry Cooling PE ANNEALING 10 min PE T C + D T C D Appearance of a second crystalline phase after an annealing step in the PE phase. It coexists with the phase at RT and we named it D (Defective Ferroelectric) phase

31 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

32 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

33 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

34 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

35 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

36 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition Curie transition χ C (%) Heat Flow HEATING 130 T ( C) COOLING Time

37 Annealing 10 min 130 C Evolution upon temperature cycle (WAXS & DSC) 10/16 30 C 130 C 30 C Inter-planar distance (nm) PE PE D Area peaks ratio Curie transition Curie transition χ C (%) 25 % 45 % Heat Flow HEATING 130 T ( C) COOLING Time

38 Model 11/16 Two main conclusions : - crystallisation in the PE phase upon heating - appareance of the D phase upon cooling

39 Model 11/16 Two main conclusions : - crystallisation in the PE phase upon heating - appareance of the D phase upon cooling Formation of crystals during solvent evaporation Part of chains with gauche chemical defects are expelled from the crystals and stayed at the interface crystal/amorphous

40 Model 11/16 Two main conclusions : - crystallisation in the PE phase upon heating - appareance of the D phase upon cooling Formation of crystals during solvent evaporation Part of chains with gauche chemical defects are expelled from the crystals and stayed at the interface crystal/amorphous Trans and gauche conformations are allowed in conformationnaly disorder PE phase Crystallization of defective part of chains at the border of PE crystals

41 Model 11/16 Two main conclusions : - crystallisation in the PE phase upon heating - appareance of the D phase upon cooling Formation of crystals during solvent evaporation Part of chains with gauche chemical defects are expelled from the crystals and stayed at the interface crystal/amorphous Trans and gauche conformations are allowed in conformationnaly disorder PE phase Crystallization of defective part of chains at the border of PE crystals Part of PE phase transits discontinuously to phase at T C Part of PE phase transists continuously to D phase

42 Influence of poling on annealed sample 12/16 WAXS (25 C) Annealed sample 30 % D 70 % Annealed and poled sample 5 % D 95 %

43 Influence of poling on annealed sample 12/16 WAXS (25 C) DSC (10 C/min) 30 % D Annealed sample 70 % + D T m T C PE Melt PE Melt Annealed and poled sample 5 % D 95 % ΔH C : 17 J/g 25 J/g ΔH m : 30 J/g constant Increase of the phase content No change in the PE phase content

44 Influence of poling on annealed sample 12/16 WAXS (25 C) DSC (10 C/min) 30 % D Annealed sample 70 % + D T m T C PE Melt PE Melt Annealed and poled sample 5 % D 95 % ΔH C : 17 J/g 25 J/g ΔH m : 30 J/g constant Increase of the phase content No change in the PE phase content Poling treatment induces the transition of the D phase to the phase

45 Model: evolution with annealing and poling 13/16

46 The D PE phase transition 14/16 The phase transition between the D phase and the PE phase has also been studied:

47 The D PE phase transition 14/16 The phase transition between the D phase and the PE phase has also been studied: Continuous evolution of inter-reticular distance (a and b cell parameters) with temperature due to the progressive change of trans in gauche conformations Correlated behavior between D peak s position and peak s width Evolution of orthorhombic symmetry (D) to hexagonal symmetry (PE)

48 The D PE phase transition 14/16 The phase transition between the D phase and the PE phase has also been studied: Continuous evolution of inter-reticular distance (a and b cell parameters) with temperature due to the progressive change of trans in gauche conformations Correlated behavior between D peak s position and peak s width Evolution of orthorhombic symmetry (D) to hexagonal symmetry (PE) Modulation of the temperature range of the transition according to annealing procedure. The phase transition can occur before or during the Curie transition ( to PE) Good correlation between different experiments: WAXS, SAXS, DSC, FTIR and DMA

49 The D PE phase transition 14/16 The phase transition between the D phase and the PE phase has also been studied: Continuous evolution of inter-reticular distance (a and b cell parameters) with temperature due to the progressive change of trans in gauche conformations Correlated behavior between D peak s position and peak s width Evolution of orthorhombic symmetry (D) to hexagonal symmetry (PE) Modulation of the temperature range of the transition according to annealing procedure. The phase transition can occur before or during the Curie transition ( to PE) Good correlation between different experiments: WAXS, SAXS, DSC, FTIR and DMA Article in review Bargain François, Panine Pierre, Domingues Dos Santos Fabrice, Tencé-Girault Sylvie. Polymer.

50 Conclusion and perspectives 15/16 Understanding changes occuring during annealing and poling steps to improve electroactive properties of poly(vdf-co-tr) films for organic electronics applications Studying the thermal phase transition between the orthorhombic Defective Ferroelectric (D) phase and the hexagonal Paraelectric (PE) phase Understanding the role of defects in PVDF-based copolymers to develop materials with interesting electro-active properties

51 16/16 Thank you for your attention Questions?