Solution-Processed Flexible Memory Devices

Dr. Nadine Gergel-HackettDr. Behrang Hamadani

Dr. Curt RichterDr. David Gundlach

Technology

MotivationFlexible electronics is an emerging industry that “sprays” electronic devices onto inexpensive plastic sheets(like inkjet printer on an overhead transparency)

Problem: Currently no method exists in flexible electronics for fabricating non-volatile low operation voltage memory devices ie devices that “hold” written state without an applied voltage

Completed design and fabrication of electronic memory devices on inexpensive plastic substrates

actual devices

Commercial Applications

Integrated Sensor is Structure – T. Clark/DARPA

sensor pack

power supplyprocessor &RFID communication

Memory indisplay

Sensor Tape – J. Ricklin/DARPA

Flexible memory devices would have applications in almost all flexible electronics circuits, some possible uses of flexible electronics include:

Advantages of Method of Device Fabrication:

• Can be performed at room temperature and pressure

• Simplified design

• Inexpensive fabrication procedures

Technology - Combining separate existing technologies

(a)Contact

Contact

Flexible Substrate

Sol gel

TiO2

actual devices

Technology•Devices showed an electrical switching with memory behavior

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6-4x10-4

-2x10-4

0

2x10-4

4x10-4

Cur

rent

(A

)

Voltage (V)

Electrical characteristics of device

Technology Applications

Areas for Improvement:

“write” and “erase” voltage values, and on/off ratios vary between devices, and increase with operation

Devices switched maximum of <10 times before permanently remaining in high state

Source of electrical switching behavior not yet well studied

-4 -2 0 2 4

-5.0x10-3

0.0

5.0x10-3

1.0x10-2

Cur

rent

(A

)

Voltage (V)

1

2

3

4

5

6

Technology Applications

0 20 40 60 80

-28.0

-24.5

-21.0

-17.5

-14.0

-10.5

-7.0

-3.5

0.0

3.5

7.0

logic

"0" logic "0"

Vol

tage

App

lied

(V)

Time (s)

logic "1"

readreadread

write

erase

Cur

rent

(A

)

0.02

0.01

0.00

-0.01

Potential Applications :The Missing Piece for the Realization of Flexible Electronics

DisplaySensors

Logic

(computing)

Memory (Low

Power,

Re-Write

able)

“Solution-Processed Flexible Titanium Dioxide Memory Devices”

Provisional patent application filed 1/22/08serial # 51/022,534

Licensing & Collaboration Opportunity

Contact Information

Nadine Gergel-Hackett, Ph.D301-975-8755nadinegh@nist.gov

David Gundlach, Ph.D301-975-2048david.gundlach@nist.gov

Curt Richter, Ph.D.301-975-2082curt.richter@nist.gov