Structure-Function Relationships in Organic Field Effect Transistors Kirsten Parratt Summer 2011 Loo Group.

Structure-Function Relationships in Organic Field Effect Transistors

Kirsten ParrattSummer 2011

Loo Group

Why Organic Semiconductors?

An alternative to inorganic electronics:• Easier manufacturing• Low temperature processing• Solution processing • Lower costs• Flexible substrates

What are Organic Semiconductors?

What advantages do they offer?

Image:s http://www.konarka.com/index.php/power-plastic/about-power-plastic/http://www.physorg.com/news/2011-02-carbon-nanotube-transistors-inexpensive-flexible.html

How it works-Physical

Silicon

Silicon OxideActive Layer

Gold Contacts

-60 -40 -20 0 20 40

0

1x10-3

2x10-3

3x10-3

4x10-3

5x10-3

6x10-3

7x10-3

[IS

D]1/

2 (A1/

2)

Gate Voltage (V)

Devices

SS

Si

Si

SS

Si

Si

Cl Cl

TesADT

Cl-TesADT

Processing Steps:•Weigh out compounds•Dissolve in solution•Clean SiO2 wafer•Spincast/dropcast onto substrate•Evaporate gold contacts

Device Results

0 20 40 60 80 10010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1M

ob

ilit

y (

cm

2 /Vs

)

%ClTesADT

AFM

0 mol%62.5 mol% 100 mol%

50 mol%

0 20 40 60 80 1001E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

Mo

bil

ity

(c

m^

2/V

s)

%ClTesADT

DSC

0.0 12.5 25.0 37.5 50.0 62.5 75.0 87.5 100.0120

140

160

180

200

220

240

260

280

Me

ltin

g P

oin

t (o

C)

%ClTesADT

Eutectic Grain Boundaries

Conclusion

• At 62.5% ClTesADT and 37.5%TesADT, a eutectic point forms

• This eutectic point has the highest intermixing and therefore the greatest grain connectivity

• As a result, OFETs with this molecular structure have higher hole mobility and function better

• Future work could involve other TesADT derivatives

Acknowledgements

• Professor Loo• Stephanie Lee• Loo Lab Group• Princeton Environmental Institute

qxy

(A-1)

q z (A

-1)

0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

qxy (A-1)q z

(A-1

)

0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

qxy

(A-1)

q z (A

-1)

0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

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0.9

qxy

(A-1)

q z (A

-1)

0.6 0.8 1 1.2 1.4 1.6 1.80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

qxy

(A-1)

q z (A

-1)

0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

qxy

(A-1)

q z (A

-1)

0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

12.5mol% 37.5mol% 50mol%

62.5mol% 87.5mol% 100mol%

GIXD