Investigate unoccupied states of homologous oligofluorenes by inverse photoemission spectroscopy
Date Issued
2006
Date
2006
Author(s)
Cho, Meng-Yi
DOI
en-US
Abstract
Because of the multilayer structure of organic light emitting diode（OLED）,the interaction between each organic thin films is important for the electroluminescent devices. Therefore, we are interested in the surface and interface between the organic thin films. The UPS and IPES are the most powerful and direct technologies to study the structure of occupied and unoccupied energy band below and above the Fermi level in the solid state material, respectively. In this thesis, we would introduce the basic concept of OLED and IPES, and study the IPES spectra of organic materials via the system introduced. Here, we chose homologous oligifluorenes, T3 and B4, to investigate because the fluorene-based materials are attractive in the field of the blue emitter. Therefore, we would present the IPES spectra of T3 and B4 to find their LUMO onset. Compared with the calculated IPES spectrum, we find that the calculated spectrum agree approximately with the measured one, especially for the portion with the energies between 2~4 eV. The combined PES and IPES spectra gives the energy gap Eg between the peak onset. However, the IPES peaks are not as clearly defined between 0~4 eV. We hope to measure better IPES spectra and well define the IPES peaks of all the homologous oligofluorenes and then combine PES and IPES spectra to give us more information about surface and interface around the Fermi level in the future.
Subjects
光電子頻譜
寡聚芴
inverse photoemission spectroscopy
unoccupied
homologous oligofluorenes
Type
thesis
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