Simulation to charge injection and transport in OLED

1
Simulation to charge injection and transport in
OLED

• Speaker ???
• Adviser Dr.???

2
outline

• motivation
• Charge injection issue
• Overview of charge injection
• Charge transport
• Experiment Simulation
• Conclusion
• Simulation to charge injection and transport in
  OLED

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Motivation of development of organic electronic
devices

• low cost and various kinds of substrate
• Traditional devices restrict to silicon
  substrate, though with a better performance.
• Attractive application
• the novel flat-panel display technology based on
  OLED.

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Obstacles

• Research difficulties
• Complexity of interface
• Hard to experimentally measure trap distribution
• Necessity
• electrical contact with other components
• significant issue if new material
• Goal
• To overcome energy barrier.

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Overview of Charge injection
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Early theories

• Fowler-Nordheim theory Richard-Schottky theory
• fail to consider the amorphous nature of the
  organic.
• Amorphous, not crystalline
• Organic, not semiconductor
• However,
• J 8 mobility DOS
• Monti-Carlo Simulation (1993)

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Energy diagram of RS FN
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Theory in 2003

• the barrier height
• the image potential
• applied voltage
• disorder

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Charge transport
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2 characteristics of OLED

• insulator
• Eg large-gtn0 very small
• V large -gt ni large
• When nigtgtn0 -gt SCLC
• Disorder
• Molecule, not lattice
• Poole-Frenkel effect

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Murgatroyd vs. Barbe

• L1e-5 cm
• u1e-5 (cm/s)/(v/cm)
• die58.85e-14 F/cm
• V0.5
• T27150 C

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Experiment simulation
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experiment

• Goal
• Work ft dependence of OLED
• Check temperature dependence of OLED
• Device structure
• Al/Alq/various cathodes
• Not aim to light
• Data
• Not yet

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simulationSCLC Frenkel thermal carrier
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Conclusion future work

• While SCLC theory has describe charge transport
  very well, a comprehensive theory to charge
  injection is needed.
• For transport, find out the Temperature
  dependence.
• For injection, find out the work function
  dependence.

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reference

• M. A. Baldo and S. R. Forrest PHYSICAL REVIEW B,
  VOLUME 64, 085201
• J. Campbell ScottJ. Vac. Sci. Technol. A 21.3.
• M. A. Lampert,current injection in solids