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Low-Molecular-Weight Materials: Hole Injection Materials

  • Hirohiko FukagawaEmail author
Living reference work entry

Abstract

Low-molecular-weight hole injection materials (HIMs) are categorized as small molecules with a strong acceptor and metal oxides, and halogen derivatives. Since the relationship between the substrate work function and the ionization energy of an organic layer is important for considering the hole injection barrier, not only the HIM-dependent OLED characteristics but also the energy diagram between the anode and HIM has been extensively studied using a Kelvin probe and by ultraviolet photoelectron spectroscopy. The hole injection barrier is defined as the energy difference between the Fermi level of the anode and the highest occupied molecular orbital level of the organic layer on the anode. In this chapter, both the improvement of device characteristics using HIMs and the detailed hole injection mechanisms are summarized.

Keywords

Hole injection Electron transfer Surface work function 

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Copyright information

© Springer Japan KK, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Science & Technology Research LaboratoriesJapan Broadcasting Corporation (NHK)TokyoJapan

Section editors and affiliations

  • Hironori Kaji
    • 1
  1. 1.Division of Environmental Chemistry, Institute for Chemical ResearchKyoto UniversityKyotoJapan

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