Photoelectron Spectrometer XPS and UPS

What is the Problem? 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? 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.

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.File:800px-Surface electron spectroscopies.jpg