OU

TLIN

E

Lect. 2:

Synthetic Methods toward Organic Semiconductors

Lect. 1:

Organic semiconductors: Bandgap Engineering.

Organic Semiconductors

Outline Part 2

Introduction

Material specifications

Direct synthetic routes

Precursor routes

Poly(Phenylene Vinylene) (PPV)

n

OC1C10-PPV

O

O

n

Sn

RR-Poly(3-HexylThiophene) (P3HT)n

H17C8 C8H17

Poly(DiOctyl-Fluorene) (PDOF)Plastic Electronics

Applications as Semi-Conductor

(MDMO-PPV or OC1C10-PPV or MEH-PPV) and conjugated polymer

Workhorse materials in plastic electronics

P3HT and conjugated polymer

Workhorse materials in plastic electronics

(LBG or low bandgap or low band gap) and conjugated polymer

Workhorse materials in plastic electronics

Plastic Electronics

Printed Electronics

Outline Part 2

Introduction

Material specifications

Direct synthetic routes

Precursor routes

Synthesis of Conjugated Polymers

N

SN

S S

n

Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-CycloPenta[2,1-b;3,4-b′]-

DiThiophene)-alt-4,7-(2,1,3-BenzoThiadiazole)]

PCPDTBT

Material Specifications

Low Defect Level in Conjugated System

High Mobility of Charge Carriers

Appropriate Electrochemical properties ( Eox

and Ered)

High Thermal Stability of the Conjugated System

(some cases) Supramolecular Order

Elektronic Specifications

Simple Monomer Synthesis

Straightforward polymerization chemistry

Processible from common solvents

Sufficient High Molecular Weight ( Mn > 25 000 )

Reasonable polydispersity (1 < PD < 3)

High Thermal Stability

Polymer Specifications

Material Specifications

Purification and fractionation

Recycling GPC

Wataru S. et al. Org. Biomol. Chem., 2014, 12, 3354–3357

Scalability of the synthesisPo R. et al., Macromolecules (2015), DOI: 10.1021/ma501894w

Synthetic Complexity

nPPV

O

O

BrBr

+

CHO

CHOP(C6H5)3Cl

P(C6H5)3Cl

+

McMurry Reaction (TiCl4/Zn,THF)

Heck Reaction

Wittig Reaction (Base)

(Pd(OAc)2/Base)

Synthesis of PPV

XC8H17H17C8X

HOOC COOH

S

XC8H17H17C8X

S

S

XC8H17H17C8X

O

S

XC8H17H17C8X

O OH

S

XC8H17H17C8X

OO

O

XC8H17H17C8X

OO

X = S (a), O (b)

O

O

14 15 16

OHHO

MeOOC COOMe

OC8H17H17C8O

MeOOC COOMe

vi

ClCl

HOOC COOH

SC8H17H17C8S

EtOOC COOEt

9 10 11

17a,b 18a,b 19a,b

20a,b 21a,b 22a,b

13

OTMSTMSO

MeOOC COOMe

iii

ivTMSO OTMS

v

12

ClCl

EtOOC COOEt

i ii

vii viii ix

x xi xii

S

SC8H17H17C8S

n

Low Band Gap Conjugated Polymers

Outline part 2

Introduction

Material specifications

Direct synthetic routes

Precursor routes

Outline part 2

Direct synthetic routes

Oxidative polymerization

McCullough method

Rieke Method

Suziki coupling

Stille and Sonogashira coupling

Yamamoto Coupling

Precursor routes

Oxidative Polymerization

S

FeCl3, CHCl3

Sn

Ar

Ar

NC

CN

n

OC

10H

21

H21

C10

O

Ar

Ar

NC

CN

OC10

H21

H21

C10

O

S S

OO

S

C8H

17

S

OO

C14

H29

Ar =

FeCl3

CHCl3

a b c d

5 6

Oxidative Polymerization

S

FeCl3

S S

S

2 S

S

S

S

- 2H+S

S

FeCl3

S

S+

S

S

S S

S

S

S

- 2H+

H

Oxidative Polymerization

S

FeCl3

S S

S

S

S

n-2

S

S

S

n-2

- 2H+

S

S

S

S

n-2

S

S

S

S

n-1

FeCl3

SBr Br

R

SBrZn Br

RNi(dppe)Cl2

b.

Negishi Coupling

> 98% Regioregular

SBrMg Br

R

SBr

R

Ni(dppe)Cl2

S

R

n

a.

Kumada Coupling

Poly(Alkyl Thiophene) (PAT)

S

R

SS

e

R

F Cl3S S

R

S

R

R

S

R R

75%

25%

a. McCullough R. D., Lowe R.D.; J. Chem. Soc. Chem. Commun., 70 (1992)

b. Chen T-A., Rieke R. D.; J. Am. Chem. Soc., 114,10087 (1992)

Regio-Regular Conjugated Polymers

Nobel prize 2010

Chemistry

Mechanism of cross-coupling

R MMX

Reductive elimination

heterocyclic sp2

carbon atom

oxidative addition

transmetalation

R

Pd X

Pd R

XPd(0)

I. Osaka and R. D. McCullough, Acc. Chem. Res., 41, 1202-1214 (2008)

E. L. Lanni and A. J. McNeil, J. Am. Chem. Soc. 131, 16573-16579 (2009)

Regioregular P3ATs

GPC (MW vs PS) 1H-NMR UV-Vis DSC

m Yield

%

Mn

/103

Mw

/103

PD RR lmax / nm

(CHCl3)

Tm /

°C

(peak)

3 - - - 96.1 290

4 75 19.5 44.7 2.29 96.5 281

5 79 16.7 32.3 1.93 94.5 451 249

6 80 23.7 42.6 1.80 94.5 450 234

7 67 24.4 39.9 1.64 97 451 198

8 73 28.0 46.5 1.66 97 451 210

9 50 25.9 37.8 1.46 98 449 187

S

CmH2m + 1

n

**

P3mT

‘P3HT’

= P36T

Rieke coupling

W. Oosterbaan et al., J. Mat. Chem. 19, 5424-5435 (2009)

Fiber formation & isolation

Example: 0.5 wt % P35T in p-Xylene:

1. Dissolve at 80 °C clear orange solution

2. Slowly cool to room temperature colour changes to dark red

3. Isolation by centrifugation

300 400 500 600 700 800

0.0

0.5

1.0

Norm

aliz

ed A

bsorb

ance

l / nm

Supernatant

Pristine dispersion

Fiber

AFM (tapping mode, 1 x 1 mm)

P34T

P39T

P33T

P37T

P35T

Fiber sizes:

Height: 5—10 nm

Width: 20 nm

Length: 0.5—4 mm

W. Oosterbaan et al., J. Mat. Chem. 19, 5424-5435 (2009)

Poly(p-Phenylene) Derivatives

Suzuki Coupling

n

B

OH

OH

B

HO

HOBrBr+

K2CO3

Pd(PPh3)4

nH17C8 C8H17

Poly(dioctyl-fluorene) (PDOF)

Nobel prize 2010

ChemistryM. Seki, Synthesis 18, 2975-2992 (2006)

Other cross-couplings

SBrBr

Pd(PPh3)4SSn(CH3)3(CH3)3Sn

+

n

S

S

Stille cross-coupling

Sonogashira cross-coupling

SBrBr

CuI, Pd(PPh3)4S+

nS

S

M. Seki, Synthesis 18, 2975-2992 (2006)

Other cross-couplings

Yamamoto cross-coupling

SBrBr

Ni(COD)2

nS

N. Blouin and M. Leclerc, Acc. Chem. Res. 41 (9), 1110-1119 (2008)

N

SN

S S

n

Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-CycloPenta[2,1-b;3,4-b′]-

DiThiophene)-alt-4,7-(2,1,3-BenzoThiadiazole)]

PCPDTBT

Low Bandgap Polymers?

Low Bandgap Polymers?

Bundgaard, E., Krebs, F. C., Sol. Energy Mater. Sol. Cells 2007, 91, 954

N

SN

S S

n

Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-

CycloPenta[2,1-b;3,4-b′]-

DiThiophene)-alt-4,7-(2,1,3-

BenzoThiadiazole)]

PCPDTBT

6% < h < 9.0 %

Low Bandgap Polymers?

J. Roncali , Acc Chem Res (2009) 42 (11), 1719-1730

Outline

Direct synthetic routes

Oxidative polymerization

McCullough method

Rieke Method

Suziki coupling

Stille and Sonogashira coupling

Yamamoto Coupling

Precursor routes

PolyThiophene Derivatives

LBG Derivatives

Outline part 2

Introduction

Material specifications

Direct synthetic routes

Precursor routes

Precursor Routes toward Conjugated Polymers

n

Poly(Phenylene Vinylene) (PPV)

T

Pn

O

O

nOH

O

O

n

Basic

Hydrolysis

Radical

Polymerisation

F3C CF3

ROMP

T

n

F3C CF3

+

n

T

F3C CF3

n

Precursor Polymers

Feast PA Precursor route

J.H. Edwards and W. J. Feast, Polymer, 21, 595 (1980)

n

Poly(Phenylene Vinylene) (PPV)

Gilch Route (1966)

H. G. Gilch, W. L. Wheelwright; J. Polym.Sc.; part A, 4, 1337 (1966)

ClClor THF

t-BuO in dioxane

nCl

Polymerisation Reactions of Para-Quinodimethane Systems

R

n

ClCl

S S

R

RR

RClCl

t-BuOK/THF NaOH/H2O

SCl

Cl

R =

Cl

Cl

S

R

R

Polymerisation Reactions of Para-Quinodimethane Systems

1988PL

Base

PL

P

Precursor Polymer

nP

Polymerisation Reactions of Para-Quinodimethane Systems

Synthesis

Precursor Routes - General Scheme

Gilch (1966): L = P = Cl

Wessling (1968): L = P = SR2+X-

Sulfinyl (1992): L = Cl ; P = S(O)R

Xanthate (1995): L = P = SC(S)OR

Dithiocarbamate (2003): L = P = SC(S)NR2

(PPV)[

]n

L = leaving group

P = polariser

PLp-QM

P

PL

p-QMP

STEP 2

Conjugated Polymer

P

[

]n

Precursor

STEP 1

STEP 3

1992

Sulphinyl Route (1992)

F. Louwet, D. Vanderzande, J. Gelan, J. Mullens; Macromolecules; 1995, 28, 1330

n

Poly(Phenylene Vinylene) (PPV)

SCl

R

O

t-BuO in sec-BuOH

S

R

O

T (70°C)

nS

R

O

Mw = 200.000; Yield = 80%

Polymerisation Reactions of Para-Quinodimethane Systems

Precursor approach

S n

Poly(2,5-Thienylene Vinylene) (PTV)

SiN

Si

Li

Lithium HexamethylDiSilazane

SS

N

SS

N

S SS

N

S

n

base

THF

H. Diliën et al., Macromolecules 43, 10231-10240 (2010)

Polymerisation Reactions of Para-Quinodimethane Systems

Highly versatile

S

OR

RO

N

RO

CN

CN

Cl

Cl

R

R

N

N

N

S

N

S

PNu

Anionic Initiation

1996

Polymerization Mechanism?

Pn

P

P

P

P

Radical Initiation

Polymerisation Reactions of Para-Quinodimethane Systems

L. Hontis et al., Macromolecules 36, 3035-3044 (2003)

I. Cosemans et al. , Macromolecules 44, 7610-7616 (2011)

44% 35%

Highly Reactive p-Systems

P. C. Hiberty, P. Karafiloglou; Theoretica Chimica Acta; 1982, 171-177.

Ortho and Para-Quinodimethane Systems

Conclusion

Several very reliable synthetic methods exist toward the synthesis of conjugated polymers

Typically they are versatile, give rise to acceptable Mw

Give rise to low defects levels in the chemical structure

In some cases efforts to avoid residues of catalysts is an issue

Purification of the resulting polymer is of great importance <=> materials should be used in electronics