- 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
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