Design And Synthesis Of High Mobility Materials And Their Application In Organic Field-effect Transistors

Design and Synthesis of High Mobility Materials and Their Application in Organic Field-Effect Transistors Yunqi Liu ( 刘云圻 ) [email protected] Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China September 22, 2008

Organic Field-effect Transistors (OFETs) Organic field-effect transistors (OFET) are active devices, whose characteristics are modulated by the electrical field ♣ Simple processability ♣ Low cost ♣ Flexibility

 Mobility  On/off  Threshold voltage

Organic FET Applications pixel drivers for active-matrix displays and detectors Philips Research

Penn State Univ.

Univ. Tokyo

Radio-frequency Identification tags

Wireless power transmission

Electronic paper

Organic Semiconductors Polymers

Small-molecule materials p-type

p-type

N N

S

S

S

S

S

N

S

S

n

Cu N N

N

n

N

N

S

S F

F

F

n-type

n-type

F F

O

F

O

F

F

F

N

N

N

N

F F

F n

F F

F

F

F

N

N

N

F

F

N

F

F

F

F

Cu N F

N

N

N

F

F F

F

F

F

Requirements for FET materials • Largeπ-Conjugation • Planar • Strongly π- π interaction • Crystal

Organic semiconductors Planar

Linear R

S

S

R

S

S

N S

S R R

R

S

Cyclic N

N

N

Cu

N

NH

N

N

N

NH

N

HN HN H2SO4 HN

.

NH

S

R

R

S

S

S

S

S

S

S

S

N

R

R N

R

N

O

 － conjugation

Carbon Nanotubes

S

S

S

S

TTF

Dibenzotetrathiafulvalene Bisimides: New Building Blocks for Organic Electronic Materials

 A diverse library of derivatives with various functionalities at the imide rings  An electrically active TTF core, which might endow them with novel electronic properties

Advanced Materials. 2007, 19, 3037.

LUMO

HOMO

(a)

( b)

(c)

dinterplanar

= 3.42 Å

dS−O = 3.16 Å, dS-S = 3.80 Å

Figure 3. Molecular structure (a) and stacking structures (b and c) of 1

The face-to-face columnar π -stacking and the side-by-side intercolumnar S···O and S···S contacts increase the effective dimensionality of the electronic structure and benefit charge transport

Compound 2

More than 20 devices

Three weeks

compound

HOMO (eV)

band gap (eV)

mobility (cm2/Vs)

on/off ratio

1

−5.46

2.05

0.011−0.094

106−108

2

−5.42

2.06

0.12−0.40

106−108

DBTTF

−4.97

2.79

0.001−0.003

102−103

Because of the strong electron-donating property of most TTF derivatives (i.e. their high HOMO levels), their thin film are labile to oxygen, the resulting dopants increase the conductivity of the film in the off or ungated state and lead to the poor FET performance. Thus more electron deficient TTF derivatives, having the relative low-lying HOMO levels, are promising

High-Performance Transistor Based on Individual SingleCrystalline Micrometer Wire of PET Backgroud: •

•

Fundamental aspects of carrier transport, especially the role of solid-state packing, still remain unclear Studies on micro- and nanomaterials, including fibers, ribbons, and wires are few

perylo[1,12-b,c,d]thiophene (PET ) and its crystal packing

The extraordinary solid-state packing arrangement with the likelihood of double-channel fashion induced by marked S···S interactions J. Am. Chem. Soc. 2007, 129, 1882.

FETs made of thin films -3

-80 V

-5

1x10

-8 -60 V

-6 -4

-40 V

-2

-20 V 0V

0 0

-20

-40

-60

Drain voltage (V)

Characteristics of thin-film transistor based on PET at room temperature

-80

Drain current (A)

Drain current ( µA)

-10

6.0x10

VD = -80 V

-3

5.0x10

Drain current 1/2 (A 1/2 )

-12

-6

10

-3

4.0x10

-7

3.0x10

-8

2.0x10

-9

1.0x10

-3

10

-3

10

-3

10

0.0

-10

10

0

-20

-40 -60 -80 Gate voltage (V)

-100

mobility : 0.05 cm2/Vs, an on/off ratio: 1.2×105, threshold voltage : -6.3 V, subthreshold swing: 4 V per decade

Fabrication of FETs with single crystals wire

Transistors based on an individual single-crystalline micrometer wire of PET have been fabricated with a gold wire as mask.

W: L:

1.8 µ m 55 µ m

mobility : 0.8 cm2/Vs, an on/off ratio: 1.7×103, threshold voltage : -6 V, Six transistors, mobility : 0.3-0.8 cm2/Vs, Good stability in air

Shelf-life test for one transistor under ambients for one week, mobility only from 0.35 to 0.34 cm2/Vs and on/off ratio unchanged

Single-Crystal Microribbons of an Indolo[3,2b]carbazole Derivative by Solution-Phase Self-Assembly with Novel Mechanical, Electrical and Optical Properties

Accepted

2TFMPOIND F 3C C8H17 N N C8 H17 CF3

      

Carbazole as a building block Extended π -conjugation Alkyl chains improve solubility π −π stacking Alkyl−alkyl close contacts F⋅ ⋅ ⋅ H hydrogen bonds Self-assembling into 1D nano/micro single crystals

Crystal structure and intermolecular interactions

Quasi-planar structure with a small dihedral angle of 2.56o 3.378 Å cofacial π −π stacking Alkyl-alkyl close contacts (2.301−2.331 Å, H-to-H) F⋅ ⋅ ⋅ H hydrogen bonds (2.565−2.2.600 Å) These intermolecular interactions facilitate charge transport

Field-effect transistors

L = 68 µ m, W = 1.2 µ m µ = 0.084 cm2/Vs, on/off = 104 VT = −8.7 V Stored at ambient for 32 days retained almost identical mobility

高迁移率材料与场效应晶体管 S

S

S

S

S

J. Am. Chem. Soc., 2005, 127, 13281

Adv. Funct. Mater., 2006, 16, 426 N N

O

J. Am. Chem. Soc., 2006, 128, 15940 J. Am. Chem. Soc., 2006, 128, 13058

电极修饰

J. Am. Chem. Soc., 2006, 128, 16418

Adv. Mater. ， 2008, 2008, 20, 3289

Adv. Mater. ， 2008, 20, 1286

High mobility materials and OFETs CNx

JACS 2005, 127, 15700

JACS 2005, 127, 8614

JACS 2005, 127, 2804 1.6x10 (b)

VD S = −100 V

-2

Al2O3/CNT

-2

lI DS 0.5 l(A 0.5 )

1.2x10 -3

8.0x10 -3

4.0x10 0 .0

Adv. Mater., 2006, 18, 181

TiOPc

Adv. Mater. 2007, 19, 2613

-10 0 -50

0

VG S (V )

50

Adv. Mater. 2008, 20, 611

100

OFETs based on micro/nano single crystals CuPc 1 µ m

CuTCNQ Adv. Mater., 2005, 17, 2953

1µ m

Adv. Mater., 2006, 18, 6568

Adv. Mater., 2006, 18, 3010 5µ m

100-400 nm 500 nm

5µ m 111

J. Am. Chem. Soc., 2006, 128, 12922

Adv. Mater., 2007, 19, 2624

011 Adv. Mater., 2008, 20, 1511

Research Roadmap of OFETs

Materials

Device s

Circuits & Functionality

SemiconductorsHigh perform. Processing Tech. p-type & n-typeParam. printing Electrodes ink-jet modula. Dielectrics lithography Interface

Integration

Chem. & Condensed Structure

Electro nic Propert

RFID E-paper Displayer

Application

Acknowledgements Funding:

NSFC, MOST, CAS Daoben Zhu, Wenping Hu, Jingui Qin, Deqing Zhang, Zhaohui Wang, Zhigang Shuai, Wei Xu, Gui Yu, Buxing Han, Kai Xiao, Yanming Sun, Ying Wang, Lei Fu, Chongan Di, Hengjun Zhang, Xike Gao, Xianglong Li