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D.S.H. Charrier

L ong term project. PEDOT:PSS. Process partially explained…. O rganic actuator and memory based on PEDOT:PSS. Dimitri S.H. Charrier. D.S.H. Charrier. L ong term project. PEDOT:PSS. Process partially explained…. 1. 2. 3. Long term project. SKPM potentiometry. STM potentiometry.

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D.S.H. Charrier

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  1. Long term project. PEDOT:PSS. Process partially explained… Organic actuator and memory based on PEDOT:PSS Dimitri S.H. Charrier D.S.H. Charrier

  2. Long term project. PEDOT:PSS. Process partially explained… 1 2 3 • Long term project. • SKPM potentiometry. • STM potentiometry. • A detour… • PEDOT:PSS. • Giant actuation. • Memory. • Process partially explained… • Drying effect. • Sorbitol. } on high performance organics D.S.H. Charrier

  3. Long term project. PEDOT:PSS. Process partially explained… • SKPM potentiometry. • STM potentiometry. • A detour… 1 2 3 • Long term project. • SKPM potentiometry. • STM potentiometry. • A detour... • PEDOT:PSS. • Giant actuation. • Memory. • Process partially explained… • Drying effect. • Sorbitol. D.S.H. Charrier

  4. Long term project. PEDOT:PSS. Process partially explained… • SKPM potentiometry. • STM potentiometry. • A detour… lever tip active layer drain source dielectric gate P3HT T = 165 K L. Bürgi et al, Synthetic Metals, 146, 297 (2004) simulated with COMSOL and MatLab Our results on test devices patterned in clean room D. Charrier et al, submitted D.S.H. Charrier

  5. Long term project. PEDOT:PSS. Process partially explained… • SKPM potentiometry. • STM potentiometry. • A detour… • SKPM potentiometry. • STM potentiometry. • A detour… Home built electronic control STM head UHV chamber D.S.H. Charrier

  6. Long term project. PEDOT:PSS. Process partially explained… • SKPM potentiometry. • STM potentiometry. • A detour… before field after field PEDOT:PSS as active layer (thickness: 60-70 nm) A huge height increase = 230 nm PEDOT PSS Typical polymer used for organic actuation, polypyrrole = PPy. Largest Strain (elongation) = 36.7 % Redox reactions involveld, PPy↔PPy+. Anionic counter ions to maintain charge neutrality. S. Hara et al, Synthetic Metals, 156, 351 (2006) D.S.H. Charrier

  7. Long term project. PEDOT:PSS. Process partially explained… • Giant actuation. • Memory. 1 2 3 • Long term project. • SKPM potentiometry. • STM potentiometry. • A detour... • PEDOT:PSS. • Giant actuation. • Memory. • Process partially explained… • Drying effect. • Sorbitol. D.S.H. Charrier

  8. Long term project. PEDOT:PSS. Process partially explained… • Giant actuation. • Memory. Au Au SiO2 After field Before field (pristine) saturation - + A height increase of about 400% !!! Initial thickness of PEDOT:PSS = 60-80 nm Spin-coated on glass or on SiO2 D.S.H. Charrier

  9. Long term project. PEDOT:PSS. Process partially explained… • Giant actuation. • Memory. Reversible… Saturation (non reversible) + 3.7 0 - 3.7 V D.S.H. Charrier

  10. Long term project. PEDOT:PSS. Process partially explained… • Giant actuation. • Memory. Switching the bias +/- 4 V Reversible cycles > 12 zoom +4 0 -4 0 Reversible height increase of about 50% D.S.H. Charrier

  11. Long term project. PEDOT:PSS. Process partially explained… • Giant actuation. • Memory. Hint: electrochemical alteration? + 4 0.5 -4 0.5 V Best ratio we got On/Off = 466 Optimal organic memory On/Off > 10 000 D.S.H. Charrier

  12. Long term project. PEDOT:PSS. Process partially explained… • Drying effect. • Sorbitol. 1 2 3 • Long term project. • SKPM potentiometry. • STM potentiometry. • A detour... • PEDOT:PSS. • Giant actuation. • Memory. • Process partially explained… • Drying effect. • Sorbitol. D.S.H. Charrier

  13. Organic actuation. Electrical memory. Process partiallyexplained… • Drying effect. • Sorbitol. • PEDOT:PSS is hygroscopic… • At 40-60 % of H20 in air, motion for > 3.5 V • At 20 % motion for > 50 V • At 13 % no motion visible ‘wet’ ‘dry’ ‘wet’ • 2 remarks: • 2 bumps at around +/-2 V • Indication for ionic current ‘dry’ D.S.H. Charrier

  14. Organic actuation. Electrical memory. Process partiallyexplained… • Drying effect. • Sorbitol. sorbitol+anneal: more compact morphology. before after - - + no sorbitol - + (sub)conclusion: Other actuation mechanism thickness = 90-100 nm D.S.H. Charrier

  15. Organic actuation. Electrical memory. Process partiallyexplained… • Reaction ‘Wet’ ‘Dry’ ‘Sorbitol’ • At positive electrode 2 reactions may occur: • PEDOT + PSS-→ PEDOT+(PSS-) + e- (1) • Charge neutrality requires movement of PSS- to + electrode. • Large volume increase at + electrode • Requires mobile PSS (‘large size’)… • PEDOT(PSS Na) → PEDOT+(PSS-) + Na+ + e- (2) • Charge neutrality requires movement of Na+ away from + electrode. • Smaller volume change, sign can be + or - • Requires mobile Na (‘small size’) Adapted from: Elisabeth Smela, Adv. Mater. 2003, 15, 481. (Review) D.S.H. Charrier

  16. Organic actuation. Electrical memory. Process partiallyexplained… • Activation energy. F  Lchar = (4 V/4m)  40 nm ~ 40 meV (voltage/channel length  ~particle size) Can the field move any material? anneal at 200C kBT ~ 40 meV all images: 500  500 nm2, z = 20 nm, done by Alex Nardes D.S.H. Charrier

  17. Long term project. PEDOT:PSS. Process partially explained… • Color change. Color changing ? Before field After/during field - + Electrochemical reaction at + electrode or PEDOT+ moving to anode… ? ‘bluish’ Sorbitol case ‘brownish’ Electrochromic devices D.S.H. Charrier

  18. Long term project. PEDOT:PSS. Process partially explained… • Color change. Reaction ? PEDOT to + ? ? www.baytron.com D.S.H. Charrier

  19. Organic actuation. Electrical memory. Process partially explained… • Conclusions • Prediction of SKPM response via 3D modeling • STM as alternative to SKPM: in progress • Giant actuation based on PEDOT:PSS • Organic memory based on PEDOT:PSS encouraging • Actuation partially explained by ionic current and mass transport • Activation energy explains the motion • Optical changes visible PEDOT + PSS-→ PEDOT+(PSS-) + e- PEDOT(PSS Na) → PEDOT+(PSS-) + Na+ + e- D.S.H. Charrier

  20. Organic actuation. Electrical memory. Process partially explained… • Thanks to OED / TU/e Barry Smalbrugge Tjibbe de Vries M2N / TU/e Lukáš Břínek Martijn Kemerink Alex Nardes René Janssen Gérard Wijers D.S.H. Charrier

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