chapter 3. organic conductor. conductivity of organic materials
TRANSCRIPT
Chapter 3. Organic Conductor
Conductivity Of Organic Materials
Conductivity = en
n: number of carriers; m: mobility of the carriers
Electronic structures of Organic Molecules(1) Core electrons.(2) electrons, localized between two atom
s.(3) n electrons, located at a particular hetero
atom, usually have high orbital energy and could be promoted easily.
(4) electrons, delocalized over an array of atoms, usually have high MO energy and could be promoted easily.
Discovery of Conducting Organic Crystals
S
S
S
S
S
S
S
S
Conductivity is controlled by the phthalocyanine ring.The metal core does not interfere the conductivity.
Phthalocyanine channel
I-
Chain length: Si:12030Ge: 7440Sn:10040
Conjugated Polymers
Polyacetylene
(1) Could a charge through delocalize through the array?
(2) Is there any one dimensional conductor in principle?
(3) How a charge hop from one array to another adjacent array?
Electrical conductivity of polyacetylene
Cis-PA = 1.7 x 10-9 S/cmTrans-PA = 4.4 x 10-5 S/cm
I2 doped = 5.5 x 102 S/cmAsF5 doped = 1.2 x 103 S/cmElectrochemical Oxidation = 1 x 103 S/cm
Li doped = 2 x 102 S/cmNa doped = 101-10-2 S/cm
Polyparaphenylene (PPP)
Synthesis of Polyarylenes
2n CuCl2n
n
AlCl3
n XX
Mg or Zn Ni(0)/ Zn
n XX
Suzuki Coupling
n XX
n BBRO
RO OR
OR
+Pd (cat)
Drawbacks: low solubility.
n
Alkyl side chain for enhancing solubility
When no of phenylene units is larger than 12, the material becomes metallic after doped
Synthesis of Polythiophenes
S
O O
n
PSS
PEDOT.PSS
Polyaniline (PANI)
Conductor
Insulator
Preparation
Doping and Undoping
PANI doped with H3PO4 was found to be most stable.
NH
NH
N N NH
NH
Conductivity could go up to 200-400 S/cm after doping
Poly-4-phenylene-(E)-vinylene (PPV)
Highly insoluble
Precursor for thin film formation
Knoevenagel Condensation
(EtO)2PO OP(OEt)2
R
R
O OR'
R'H H
+t-BuOK
R
R
R'
R'
Wittig Horner reaction
RClCl
t-BuOK
Cl+
R
Hsieh, B. R. (Xerox)
Lithium Battery
Rechargeable BatteryWith PA electrode
Oxidation(CH)x+xy(ClO4
-)
[(CH)+y(ClO4-)y]x + xye-
Reduction(CH)x+xy(Li+) + xye-
[(CH)-y(Li+)y]x
Battery Structures based on PA(a)P type (CH)x anode/Li cathode(b)P type (CH)x anode/n type (CH)x cathode(c)n type (CH)x anode /Li cathode
When the battery is doped at 6%, the
Voltages are 3.7, 2.5, 1.2V respectively
Rechargeable Battery
with poly-4-phenylene electrode
Organic Photoconductors
excited stateground stateh
Scher-Montrol Theory on dispersive photocurrent
Organic Photoconductors(1) Conjugated polymers(2) Polymers containing aromatic side-chains(3) Small molecules
Organic Solar Cell
Organic Solar Cell
Example
Self-Organized Discotic Liquid Crystals for High-Efficiency Organic Photovoltaics