| 摘要 |
PROBLEM TO BE SOLVED: To provide an element of low driving voltage and high luminous efficiency by comprising a hole injection layer between an EL layer and an anode, and including a material of less than a predetermined value of the ionization potential and a material of more than a predetermined value of ionization potential in the hole injection layer. SOLUTION: A hole injection layer includes a material with a ionization potential of 5.50 eV or below and a material with an ionization potential of 5.60 eV or above. The material with an ionization potential of 5.50 eV or below is a hole transporting material (for example, oxadiazol, oxazol, triazol and the like), and a material with an ionization potential of 5.60 eV or above is a charge generating material (for example, a-Se-based material, a-Si-based material, polyvinyl carbazol, poly-N-ethylene unsaturated group substituted- phenothiazines and the like), and the injection barrier of the hole from the electrode can be lowered by also using a photoconductive material, and utilizing the light emitted from the EL layer.
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