Simple formation method of vanadium oxide films with gap states for application in organic optoelectronics

• The simple method to form VOx with high density of gap states were investigated.
• The percentage of V2O5 change from 82.7% to 29.3% by control deposition rate.
• A number of gap states relating to oxygen vacancies was induced near the Fermi level.
• Gap states play a role of transporting charges and lowering the hole injection barrier.
• Insertion of VOx reduce the operation voltage of OLED at 1 mA/cm2 from 8.3 to 5.2 V

The simple and cost-effective method to form vanadium oxides (VOx) with high density of gap-states and role of gap-states for organic electronics were investigated. The percentage of V2O5 decreased from 82.7% to 29.3% as the deposition rate increased from 0.1 to 1.0 Å/s in thermal evaporation. Synchrotron radiation photo emission spectroscopy revealed that a number of gap states relating to oxygen vacancies was induced near the Fermi level, transporting charges and lowering the hole injection barrier from 0.92 to 0.67 eV. As a result, the operation voltage at 1 mA/cm2 was reduced from 8.3 to 5.2 V

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