- 1 -

•Humidity Sensitive Conductivity of Br-doped BEDO-TTF RDP Film

•Ultra-fast Highly Efficient Photo-Induced Phase Transition of

　　 (EDO-TTF)2PF6

•A new donor molecule, TP-EDOT

EthylenedioxyEthylenedioxy Substituted Substituted TTF'sTTF's------ previous, present, and futureprevious, present, and future

Hideki YamochiResearch Center for Low Temperature and Materials Sciences, Kyoto University

http://www.ossc.kuchem.kyoto-u.ac.jp/yamochi/index.html

2005.1.26 Rennes1

S

S

S

SO

O O

O

S

S

S

SO

O

S

S

O

OS

- 2 -

Humidity Sensitive Conductivity of Br-dopedBEDO-TTF RDP Film — Self-assembly of BO

AcknowledgementProfessor F. Wudl and his group members (UCSB → UCLA)Professor J. Ulanski, Dr. J.K. Jestzka, Dr. A. Tracz (Lodz)Professor T. Nakamura and his group members (Hokkaido)Professor S. Koshihara and his group members (TIT)Dr. Y. Inayoshi and her group members (Aoyama)Professor K. Yakushi, Dr. O. Drozdova (IMS)Professors T. Ishiguro, K. Matsumoto, T. Goto

and their group members (Kyoto)In our group: Mr. T. Kikuchi, Dr. S. Horiuchi, Mr. T. Senga,

Dr. A. Otsuka, Dr. M. Maesato, Dr. K. Tsutsumi, Mr. S. Sekizaki, Mrs. C. Tada, Mr. T. Kawasaki, Mr. Y. Nagata, Mr. H. Sasaki, Mr. T. Aoki, Dr. Y. Yoshida, Mr. A. Ota, Mr. T. Haneda, Mr. M. Soeda

Since too many numbers of colleagues worked, the full list is not available here.

S

S

S

SO

O O

O

BEDO-TTF (BO)

SS

SS

SS

SS

OO

SS

SS

OO

Weight ⇓Size ⇓

⇒⇒

Phonon Freq. ⇑Band Width ⇓

⇒ Tc ⇑

Synthesis

O

O Cl

Cl+ N

S

S

O

O S

S NMe2

NMe2

S

S

refluxCH3CN O

OS

S NMe2 110°DMSO

Br2 0°CH2Cl2

O

O

S

SBr

NMe2

Br

O

O

S

SNMe2

Br 110°25 Torr O

O

S

SSe H2Se

MeOH

(MeO)3Preflux in Bz O

O

S

S

S

S

O

O

48 % 58 %

84 % 92 % 89 %

63 %T.Suzuki, H.Yamochi, G.Srdanov, K.Hinkelmann, F.Wudl, J.Am.Chem.Soc.,111, 3108(1989)

AimBirth of the First Etylenedioxy substituted TTF

- 4 -

Initial Stage in Cation Radical Preparation of BO

H. Yamochi, et al., Synthetic Metals, 41-43, 1741 (1991)

- 5 -

Superconductors based on BO

M.A. Beno, et al., Inorg. Chem., 29, 1599 (1990)

βm-(BEDO-TTF)3Cu2(NCS)3

S. Kahlich, et al., Solid State Commun., 80, 191 (1991)

(BEDO-TTF)2ReO4(H2O)

Tc = 1.06 K (onset)R = 6.8%

Tc = 0.9 - 3.5 K (onset)R = 6.9%

•Unexpectedly Low Tc•Poor Quality ofSingle CrystalsCT Complex with Organic Acceptor Molecules

- 6 -

BO Complexes with Organic Acceptor MoleculesBO afforded Metallic Complexes with the Acceptor Molecules having wide range of ∆E, Even in the form of Compressed Powder.

S. Horiuchi, et al., J. Am. Chem. Soc., 118, 8604 (1994).

- 7 -

BO Complexes: Why Organic Metals?

V vs. SCE. In 0.1 M Bu4NBF4/CH3CN

0.380.730.35TTF0.260.660.40BEDO-TTF0.230.740.51BEDT-TTF∆EE2

1/2E11/2

Appropriate Redox Property.

(2) Appropriate Conducting Path.

NC

NC

CN

CN

NC CNHCTMM2- =

(BEDO-TTF)5(HCTMM)(Ph-CN)2

Although the Crystal Structure Analyses were Difficult in General, …

(1) Partially Charge-Transferred Ground State.

- 8 -

(BEDO-TTF)5(HCTMM)(Ph-CN)2Anion & Solvent: Severe Disorder→ No Specific Interactions

between BO and Anion Layer → Self-assembling Packing Pattern of BO

2D Layered Structure3a+c

vdWS•••S = 3.60 ÅS•••O = 3.32 Å

Side-by-sideHeteroatomic Contacts

a+2c

vdWH•••O = 2.72 Å

Weak Hydrogen Bond Network

→ 2D Electronic Structure

Calculated Fermi SurfaceI3-type Packing

- 9 -

Donor Packing Patterns in Conducting BO Complexes

I3-type ( > 17 examples)

HCP-type (2 examples)

M(CN)4-type (2 examples)

DHCP-type (1 example)

Cl-type (1 example)

κ-type (1 example)

Non-I3-type AnaloguesI3-type Packing is Partially Preserved

- 10 -

Self-assembling Nature of BEDO-TTF (BO)

Although Specific Interatomic Interactions could Prohibit the Self-Assembly, in General,

I3-type ( > 17 examples)HCP-type (2 examples)M(CN)4-type (2 examples)DHCP-type (1 example)

Non-I3-typeCl-type (1 example)κ-type (1 example)

BO shows the Self-assembling Nature.Typically I3-type Packing (β"-type in BEDT-TTF).

How can we Apply this Novel Property?

- 11 -

Application of the Self-assembling NatureMetallic Langmuir-Blodgett Films

(BO)2[(MeO)2TCNQ]4 + C19H39COOH / Benzene → Horizontal Lifting / H2OσRT = 11.3 Scm-1 Metallic doun to 180 K (50 K via ESR)K. Ogasawara, et al., Jpn. J. Appl. Phys., 35, L571 (1996)

Z

C10zTCNQzBOz

S S

S S

OO

OO

C C

C C

NN

N N

CH2

H2CCH2

H2CCH2

H2CCH2

H2CCH2

CH3

Metallic LB Film which requires no Secondary TreatmentMetallic down to ca. 250 K (50 K via Thermoelectric power)

←IRESR

T. Nakamura, et al., J. Phys. Chem., 98, 1882 (1994), K. Ikegami, et al., Synth. Met., 71, 1909 (1995)

σRT = 10 Scm-1

(BO)10(C10TCNQ)4(H2O) + C19H39COOH / Benzene → Horizontal Lifting / H2O

2(BO) + 1(C21H43COOH) / CHCl3 → Horizontal Lifting / H2OσRT = 40 Scm-1 Metallic doun to 14 KH. Ohnuki, et al., Phys. Rev. B, 55, R10255 (1997)

- 12 -

Application of the Self-assembling NatureReticulate Doped Polymer (RDP) Films

Almost colorless film∼ 15 µm thicknessρ > 1012 Ωcm

BO (1 wt. %) + PC /Cl

ClCasted

at 120 °C

·Cast Film Formation

glass

·Swelling

I2 or Br2 /CH2Cl2, CHCl2-CH2Cl, or THF

5 mm

glassSurface Conducting Film1 × 103 Ω/ (≈ 10-3-10-2 Ωcm)

ca. 200 nm

glass

- 13 -

Transparent Metallic RDP Film

S. Horiuchi, et al., Mol. Cryst. Liq. Cryst., 296, 365 (1997)

J.K. Jeszka, et al., Synthetic Metals, 106, 75 (1999)

Although Br2 Doped Films are Transparent, they are Metallic.

The Most Developed Face of the Crystallites // PC Film Surface

Long Axis of BO// Transition Moment of

Visible Absorption Band⊥ Crystallite Face

→ No Absorption of Light→ Conducting // Film Surface

Structural Model of Transparent Metallic Film.

- 14 -

Recent Results on BO-Br Complex— Humidity Sensitive Electrical Resistance

(BO)2Br(H2O)3 Single Crystal

ca. 5 Torr ca. 10-2 TorrOpen to Air

Cyclic Changing of Resistance

Reversible Detaching of H2O

In Vacuum: High Resistance

In Ambient: Low Resistance

(BO)2Br(H2O)3 easily Looses Br2 under Vacuum.

Br2 Doped BO RDP Film

AtmosphereWater SaturatedDried over P2O5

Under Vacuum: Degradation by loosing Br2Wet & Dry Atmosphere: Cyclic Breathing of RDP Film

→ New Feature of Conducting CT Complexes

- 15 -

Partial Suppression of Self-assembling Nature of BO

Self-assembling Arrangement of BO

= Tight PackingArea of Layer / Donor Molecule

BEDT-TTF: 25.0 - 28.5 Å2

BEDO-TTF: 20.4 - 21.8 Å2

Introduction of Bulky Substituent Removal of an

EDO Group

S

S

S

SO

O O

O

BEDO-DBTTF

S

S

S

SO

O S

S

EOET

S

S

S

SO

OEDO-TTF

- 16 -

Recent Progress on (Recent Progress on (EDOEDO--TTFTTF))22PFPF66

Metal

Insulator

heat

coolhν

S

S

O

O S

S

S

S

OO

S

S

The investigation resulted in the observation of Molecular Deformation in MI transition.

And further proceeded to find the Ultra-fast Highly Efficient Photo-Induced Phase Transition

How we will progressHow we will progress

S

S

S

SO

OEDO-TTF

- 17 -

O

O

S

SS +

CO2Me

CO2MeS

SO

P(OEt)3O

O

S

S

S

S

CO2Me

CO2Me

O

O

S

S

S

S LiBr·H2O/HMPArt → 95°/14mmHg for 60 min95° → 150° under N2 for 30 min

65 %

52 % EDO-TTF

Removal of an EDO Group — EDO-TTFT. Mori, et al, Chem. Lett., 1279 (1990)G. C. Papavassilliou, et al.,

Mol. Cryst. Liq. Cryst., 181, 171-184 (1990)M. Iyoda, et al., Heterocycles, 54, 833-848(2001)

Complexes with TCNQ derivatives

Complete Vanishing of Self-Assembling Nature

A. Ota, et al., Mol. Cryst. Liq. Cryst., 376, 177-182 (2002)

- 18 -

EDO-TTF — Preparation of PF6 ComplexElectrooxidation (Electrocrystallization)EDO-TTF + (Bu4N)PF6/ EtOH → (EDO-TTF)2PF6

11.6 mg 68.1 mg 18 mL 0.5 µA black 12 days elongated plates

Triclinic P 1a = 7.197(0.9) Åb = 7.343(0.6)c = 11.948(1)α = 93.454(7)°β = 75.158(6)γ = 97.405(7)V = 605.0(1) Å3

Z = 1R = 5.6 %

Head-to-Tail Stacking along b-axis.Disordered Ethylene.Isotropic Rotation of PF6

-.

Almost Uniform 1D Intermolecular Overlap Integrals.

EDO-TTF was added to (+)side only, while ca. halfamount of (Bu4N)PF6 wasadded to each chamber.

- 19 -

Physical Properties of (EDO-TTF)2PF6

At ≈ 280 K, the Complex showed Metal-to-Insulator Transition.

First Order Phase Transition

- 20 -

plana

r: 0.8

º, 2.1

º

bent

: 11.1

º, 7.9

º18

0 -φ 1

, φ 2:

6.0º , 0

.3º

Distinct Molecular Deformation

PF6Rotation

Isotropic

(EDO-TTF)2PF6 — Above and Below TMI (280 K)

Overlap Integral

Uniform

from Bond

Length

0.5+

Flexibility and Adequate Size of EDO-TTF is regarded as the Origin to Mix Metal-Insulator Transition Mechanisms.

A. Ota, et al., J.Mater. Chem., 12, 2600 (2002)

Alternate

Peierls

Uniaxial

Order-Disorder

1+/0

Charge Ordering

1+

1+

0

0

- 21 -

O. Drozdova, K. Yakushi (IMS) — Raman Spectra

(EDO-TTF)2PF6 at 4.2 KEDO-TTF0.1+ and

EDO-TTF0.9+

Synthetic Metals, 133-134, 277-279 (2003).

- 22 -

O. Drozdova, K. Yakushi (IMS) — Reflection Spectra

Synthetic Metals, 133-134, 277-279 (2003), Phys. Rev., B70(7), 075107-1-8 (2004)

E // donor stack

V plays no important role in the charge localization, which is driven by U and self-trapping mechanism due to strong e-mv coupling.

first excited state:CT1|1100> (55 %)|1010> (41 %)

third excited state: CT2|0200> (78%)|1100> (16%)

second excited state:|1010> (55%)|1100> (26%)|0200> (18%)

GS:|0110> (70%)|0200> (16%)|1010> ( 9%)

- 23 -

M. Takata, S. Aoyagi, K. Kato (SPring-8)— Accurate Structure Analysis with MEM method

285 K (0.11 e/Å3) 260 K (0.13 e/Å3)Equi-Charge-Density Surface

FF

B

B

285 K 260 KDonor-Anion Distance

Difference ChargeDensities (F at 260 K)

(+)tive

Electrostatic Stabilization in Insulating Phase

Charge on Each Donor285 K: +0.6(1) e260 K: +0.8(1) e on F

+0.2(1) e on B

Angew. Chem. Int. Ed., 43(28), 3670-3673 (2004) .

- 24 -

Time Delay

Probe (white light)

Pump (1.55 eV= 12.5 × 103 cm-1)

S. Koshihara, N. Uchida, M. Chollet (TIT)— Photo-Induced Phase Transition (PIPT)

Probe 1.38 eV(11.1 × 103 cm-1)

Probe 1.70 eV(13.7 × 103 cm-1)

Thermal Transition PIPT

1.55

eV

1.70

eV

1.38

eV

1.55

eV

1.70

eV

1.38

eV

Sample

- 25 -

K. Saito, S. Ikeuchi (Tsukuba Univ.) — Calorimetry

Relaxation Method DSC

Enthalpy of transition (latent heat) ∆H = 5.0 kJ mol-1

at equilibrium Tc = 278 KEntropy of transition∆S = ∆H/Tc = 18.0 J K-1 mol-1

•Lattice Vibrationcan be (+)tive & (-)tiveusually < a few J K-1 mol-1

• Conduction Electrons≡ Free electrons ofχ = 2.5 × 10-4 emu mol-1→ 6 J K-1 mol-1

• Anion Ordering (ULT = URT × 50-60%)harmonic oscillation ⇒ 2-3 J K-1 (mol of oscillator)-1→ 6-9 J K-1 mol-1

Still 6-3 J K-1 mol-1Unharmonic oscillation of PF6in Metallic PhaseAnion is Disordered Incompletely in Metallic Phase

Chem. Phys. Lett., 401, 76-79 (2005)

- 26 -

S. Koshihara, N. Uchida, M. Chollet (TIT) — PIPT

270 K

6 × 1018 photons/cm3

(6.4 × 1014 photons/cm2) → 50 % conversion

at 180, 265 K Completes in ca. 1.5 ps

Probe

Ultra-fast, highly effective metallization

Threshold 2 × 1018 photons/cm3 at 180 K

1 photon / 500-1500 molecules

Science, 307, 86-89 (2005)

- 27 -

S. Koshihara, N. Uchida, M. Chollet (TIT) — PIPT

vibration: ca. 0.5 ps/cycle at 180 Kc = 3.00 × 1010 cm/secν = f/c ≈ 70 cm-1

85 cm-1

T↑ ⇒ softening

Strong Electron-Lattice Interaction

vibration in ∆R/R∝ 85 cm-1 Raman peak

- 28 -

Tiny good quality crystals Condition:Donor: 11.2 mg

Electrolyte: 105 mg

Solvent: EtOH

Temperature: 5º

Time: 20 h

I: 0.3 µ A

Big Crystals ( For optical and other investigation ) Condition:Donor: 11.2 mg

Electrolyte: 105 mg

Solvent: EtOH

Temperature: r.t.

Time: 10 days

I: 0.3 µ A

Under way: Time Resolved X-ray Crystal Structure Analysis— Tiny crystals prepared by Shao

Still too thick