Difference between revisions of "Photoelectron Spectrometer XPS and UPS"

From CleanEnergyWIKI
Jump to navigation Jump to search
Line 1: Line 1:
What is the Problem? [[Image:Surface_electron_spectroscopies.jpg|thumb|right|400px |XPS uses high energy X-ray photons to excite “core” electrons in the near-surface region  UPS uses lower energy photons in the deep UV region to excite valence electrons.]]
===What is the Problem?=== [[Image:Surface_electron_spectroscopies.jpg|thumb|right|400px |XPS uses high energy X-ray photons to excite “core” electrons in the near-surface region  UPS uses lower energy photons in the deep UV region to excite valence electrons.]]
OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes.  We need analytical tools which tell us:
OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes.  We need analytical tools which tell us:
*Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm)
*Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm)
Line 5: Line 5:
*The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc.
*The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc.


What is our approach?
===What is our approach? Physics of XPS and UPS===
We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials.
We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials.


[[Image:PS-surfaceanalysis.jpg|thumb|right|400px |The small sampling depth of XPS and UPS arises because most of the photoelectrons generated do NOT make it out of the solid – they are scattered below the surface and not detected.  Only those within 1-10 nm of the surface get out and can be analyzed.]]
[[Image:PS-surfaceanalysis.jpg|thumb|right|400px |The small sampling depth of XPS and UPS arises because most of the photoelectrons generated do NOT make it out of the solid – they are scattered below the surface and not detected.  Only those within 1-10 nm of the surface get out and can be analyzed.]]
===Data interpretation===

Revision as of 09:18, 22 April 2009

===What is the Problem?===

XPS uses high energy X-ray photons to excite “core” electrons in the near-surface region UPS uses lower energy photons in the deep UV region to excite valence electrons.

OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes. We need analytical tools which tell us:

  • Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm)
  • The molecular state of those elements in that same region
  • The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc.

What is our approach? Physics of XPS and UPS

We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials.

The small sampling depth of XPS and UPS arises because most of the photoelectrons generated do NOT make it out of the solid – they are scattered below the surface and not detected. Only those within 1-10 nm of the surface get out and can be analyzed.

Data interpretation