Kyung Hee University,
Keywords: quantum-dots, light emitting diodes, vanadium oxide, hole injection layer, low-temperature
Summary:Low-temperature solution processable inorganic vanadium oxide (V2O5) hole injection layer (HIL) was synthesized for flexible quantum-dots light emitting diodes (QLEDs). Efficient hole injection characteristics were observed at the hole only devices, even the process temperature of V2O5 was as low as room-temperature. The origin of the efficient hole injection was investigated by measuring ultraviolet and x-ray photoelectron spectroscopy, and we found that the density of gap states was increased according to reduce the process temperature. Therefore, QLEDs with a low-temperature solution processable V2O5 HIL was fabricated on a glass substrate, and the device showed excellent characteristics. The maximum luminance and luminous efficiency of the device were measured as 56,717 Cd/m2 and 4.03 Cd/A, respectively. Due to the low-temperature process of V2O5 HIL, it was possible to fabricate QLEDs on a flexible plastic substrate without mechanical deformation of plastic substrates, as well. The result suggests that the low-temperature V2O5 inorganic HIL is a feasible alternative to organic HILs for flexible QLEDs.