Organic semiconductor interfaces: Discrimination between charging and band bending related shifts in frontier orbital line-up measurements with photoemission spectroscopy
| Autor: | Rudy Schlaf, Lisa A. Crisafulli, Zakya H. Kafafi, Charles D. Merritt |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 86:5678-5686 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.371578 |
| Popis: | Gaq3 is a promising luminescent organic semiconductor for applications in organic light emitting diodes. The frontier orbital alignment at the tris (8-hydroxyquinolinato) gallium (Gaq3)/Pt organic Schottky contact was determined by combined x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) measurements. A Gaq3 thin film was deposited in several steps on a previously Ar+ sputtered pure Pt foil. After each growth step, the sample was characterized by XPS and UPS. The combination of XPS and UPS measurements allows the precise evaluation of the interface dipole independent from the simultaneously occurring band bending at the interface and charging artifacts. The measurements show that the Pt/Gaq3 interface has a strong dipole of 0.71 eV indicating the transfer of negative charge from Gaq3 to Pt. Due to the large work function difference between Pt and Gaq3, strong band bending occurred. At Gaq3 coverages higher than 128 A strong charging shifts occurred in the overlayer related emission lines which... |
| Databáze: | OpenAIRE |
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