Godwin St. Luce

PhD in Engineering, Micro/Nanoscale Emphasis

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*Applications of P3HT

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• History

• Introduction

• Properties

• Applications

• Advantages and Disadvantages

• Conclusions

• References

• Questions

*Overview

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History* The study of polymers have been around since WWII.

* 1992 Roncali surveyed electrochemical synthesis in Polythiophenes (PTs)

* 1990-1994 Schopf and Kobmehl published “Conductive Polymer Layers”2)

* 1997 Roncali investigated the electronic properties of substituted PTs

* 1998 McCillough’s focused on Chemical Synthesis of Conducting PTs

* 1999 Reddinger and Reynolds general review of Conducting Polymers

* 2000 Alan Heeger, Alan G. MacDiarmind and Hideki Shirakawa received

Nobel Laureates in Chemistry (Conjugated Polymers)[1]

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• Polymer is a substance containing a large number of repeated structural units join (monomers).

• Polythiophenes is a heterocyclic compound that can become conducting when electrons are added or removed from their structure via doping.

• Poly(3-hexylthiophene-2,5-diyl) known as P3HT is a conducting polymer belonging to the Polythiophenes family.

*Introduction

5MSE 504

*PropertiesConjugated Double Bonds

* As a result of the 3Sp2 orbitals and the lone e- in the (Pz) un-hybridized orbital.

* LUMO is created by the anti-bonding * orbitals and HOMO is created by the bonding orbitals. Their differences is a result of the band gap, of a semi-conductor.

* Energy Band Diagram using polymer as a

semi-conductor active layer [4]

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*Properties cont’d* Different doping of these polymers can interchange properties. Poly(3-

hexylthiophene) P3HT conductivity at 300K is 30 Scm-1 , where Poly(3-methylthiophene) has conductivity of 500 Scm-1) [3].

* Absorption Spectra of doped and un doped P3HT films @ 300K [3].

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*ApplicationsP3HT/n-c Si Transistor

* Proposed Energy Band diagram for

n-c Si/P3HT[5].

* Electron Affinity (χ)

* Conduction Band Offset (Δ)

* Valence Band Offset (Δ)

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*ApplicationsOrganic Light Emitting Diode (OLED)

* Solid-state devices composed of thin films of organic molecules

* Color of light depends on type of organic

molecule in emissive layer (P3HT).

* The intensity of light is proportional to

the applied current.

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*ApplicationsTypes of OLED

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*Advantages* Conductive Range of Conductive Polymers [7]

* Very light weight and flexible

* Cost of production

* Availability

* Properties of polymers can be altered drastically by doping.

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*Disadvantages* In n-doping the added electron is normally lost in the atmosphere.

* Absorption spectra is limited, compared to Si, GaAs etc.

* External Quantum Efficiencies (EQE) are low [6].

* They tend to be much slower than inorganic devices

* Some devices have limited life spans (OLED).

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*Conclusion* Organic polymers are the new age of electronic research.

* Properties of P3HT are close to being compared with inorganic devices.

* Can be fabricated at room temperature.

* Useful in energy storage application [8].

* Organic material are easy to process in large area.

* Some organic materials are sensitive to oxidation effects.

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[1] http://www.sigmaaldrich.com/catalog/product/aldrich/698997?lang=en&region=US

[2] http://doc.utwente.nl/9135/1/t0000022.pd

[3] http://voh.chem.ucla.edu/vohtar/fall04/classes/285/pdf/patil_ch_rev.pdf

[4] http://www.ine.uh.edu/research/organic-solar-cells/index.php

[5] http://144.206.159.178/ft/18414/933128/16265291.pdf

[6] http://nano.teicrete.gr/Microelectronics/Organic%20photovoltaics%20%20technology%20and%20market.pdf

[7] http://www.youtube.com/watch?v=WPcIYr1DkuQ

[8] http://physics.usask.ca/~chang/homepage/Organic/Organic.html

*References

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*Questions