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