Organic ElectronicsOrganic Electronics

Presented By:Presented By:

Mehrdad NajibiMehrdad Najibi

Class Presentation for Advanced VLSI CourseClass Presentation for Advanced VLSI Course

OutlinesOutlines

Introduction to Organic ElectronicsIntroduction to Organic ElectronicsApplications Applications Organic Thin-Film-Transistors (OTFTs)Organic Thin-Film-Transistors (OTFTs)Organic MaterialsOrganic MaterialsRecent AdvancesRecent AdvancesSummarySummary

What and why an organic What and why an organic transistor?transistor?

First Organic Transistor - 1986First Organic Transistor - 1986 Using organic molecules (Polymers) rather than silicon for their Using organic molecules (Polymers) rather than silicon for their

active material. active material. SemiconductorSemiconductor

AdvantagesAdvantages Less Complex & Lower-cost FabricationLess Complex & Lower-cost Fabrication

Solution Processing Solution Processing Photolithographic patterning Photolithographic patterning lower temperature manufacturing (60-120lower temperature manufacturing (60-120°° C) C) Print-able Organic TransistorsPrint-able Organic Transistors

Mechanical flexibilityMechanical flexibility compatibility with plastic substances: foldable & light weightcompatibility with plastic substances: foldable & light weight

Strong Optical Absorption and Efficient Emission

ApplicationsApplications Flexible low-weight large-Flexible low-weight large-

Area DisplaysArea Displays OLED + OTFT OLED + OTFT

Optical recording (optical absorption)

Electronic circuits printed Electronic circuits printed on paperon paper

Electronic PapersElectronic Papers Ultra Low-Cost Low-Ultra Low-Cost Low-

Performance ApplicationsPerformance Applications Smart cardsSmart cards

Low-heat dissipation Low-heat dissipation circuitscircuits

Organic Thin Film Transistors Organic Thin Film Transistors (OTFT)(OTFT)

Very Similar to Very Similar to MOSFETsMOSFETs

3-Terminal Device3-Terminal Device Voltage Controled Voltage Controled

SwitchSwitch Differences Differences

Carrier TransportCarrier Transport Discrete Energy LevelsDiscrete Energy Levels HoppingHopping

Organic Active LayerOrganic Active Layer Depletion DevicesDepletion Devices

Figure1 [1]

Organic Thin Film Transistors Organic Thin Film Transistors (OTFT)(OTFT)

Current Flow ModeCurrent Flow Mode Vth is not Constant Smaller die-electric Smaller die-electric

ConstantConstant Velocity SaturationVelocity Saturation

Due to hopping Due to hopping Is more likely to occurIs more likely to occur

Figure2 [2]

Organic Thin Film Transistors Organic Thin Film Transistors (OTFT)(OTFT)

Key ParametersKey ParametersMobility (Mobility (µ ≈ 1-10 cmµ ≈ 1-10 cm22/vs/vs))

Much Lower than SiMuch Lower than Si

On-Off RatioOn-Off RatioSuitable (10Suitable (1066))

MaterialMaterial MobilityMobility

a-Sia-Si 0.1 cm0.1 cm22/Vs/Vs

OrganicsOrganics 1-10 cm1-10 cm22/Vs/Vs

SiSi 200 cm200 cm22/Vs/Vs

Figure3 [4]

New Organic MaterialsNew Organic Materials

Challenging factorsChallenging factors PerformancePerformance Electrical ParametersElectrical Parameters Process-abilityProcess-ability

SolubilitySolubility Long-Term StabilityLong-Term Stability Regular StructureRegular Structure

Facilitate Hopping Facilitate Hopping ProcessProcess

Purify-abilityPurify-ability Impurity Impurity charge charge

trapstraps

Figure4 [1]

Progress in performance of OTFTs from 1986 to the Progress in performance of OTFTs from 1986 to the presentpresent

Figure5 [4]

SummarySummary

organic electronics is ready to meet the requirements for product realizationCompatibility with a huge variety of substrates

(web-coated polyester, paper).Reliability readouts according to product

requirements (shelf and operational lifetimes).Yield enabling profitable manufacturing.Proof of concept for simple and cheap

manufacturing methods.Realization of supply voltages down to 1 V

ReferencesReferences

[1] Colin Reese, Mark Roberts, Mang-mang Ling, and Zhenan Bao. “Organic Thin Film Transistors”, Material Study, September 2004.

[2] S. Forrest, P. Burrows, M. Thompson. “The dawn of organic electronics” , IEEE Spectrum, Vol. 37 No. 8, 2000 , IEEE Spectrum, Vol. 37 No. 8, 2000

[3] G. Paasch (1,2), S. Scheinert (1), R. Tecklenburg (2). “Theory and modeling of organic field effect transistors”

[4][4] C. D. Dimitrakopoulos, D. J. Mascaro.C. D. Dimitrakopoulos, D. J. Mascaro. “ “Organic thin-film transistors: A Organic thin-film transistors: A review of recent advances”, review of recent advances”, IBM Journal Of Research & IBM Journal Of Research & Developmenmt, Volum 45, 2001Developmenmt, Volum 45, 2001

Future Outlook: Time to Start Future Outlook: Time to Start Reviewing those Chemistry BooksReviewing those Chemistry Books

OTFTs for active-matrix (LDC) displaysOTFTs for active-matrix (LDC) displaysFlexible view screens (or anything…)Flexible view screens (or anything…)New generations of smart cards New generations of smart cards Organic smart pixels with OLEDsOrganic smart pixels with OLEDsLarge-area display electronicsLarge-area display electronicsOrganic semiconductor advances in Organic semiconductor advances in

mobility, switching time, and manufacturing mobility, switching time, and manufacturing may lead to many possibilitiesmay lead to many possibilities

Mobilities of organic semiconductors have improved by five orders of magnitude over the past 15 years. Large research efforts using materials such as these led to some of this increase.