Luminance enhancement in quantum dot light-emitting diodes fabricated with Field’s metal as the cathode


C .E.Rodríguez

This work reports the fabrication and characterization of blue–green quantum dot
light-emitting diodes (QD-LEDs) by using core/shell/shell Cd1−xZnxSe/ZnSe/ZnS quantum
dots. Poly [(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)]
(PFN) was introduced in order to enhance the electron injection and also acted as a protecting
layer during the deposition of the cathode (a Field’s metal sheet) on the organic/inorganic
active layers at low temperature (63 °C). This procedure permitted us to eliminate the process
of thermal evaporation for the deposition of metallic cathodes, which is typically used in the
fabrication of OLEDs. The performance of devices made with an aluminum cathode was
compared with that of devices which employed Field’s metal (FM) as the cathode. We found
that the luminance and efficiency of devices with FM was ~70% higher with respect to those that
employed aluminum as the cathode and their consumption of current was similar up to 13 V.
We also demonstrated that the simultaneous presence of 1,2-ethanedethiol (EDT) and PFN
enhanced the luminance in our devices and improved the current injection in QD-LEDs.
Hence, the architecture for QD-LEDs presented in this work could be useful for the
fabrication of low-cost luminescent devices.

Artículo-CERG 5 2017