Graphene oxide/PEDOT:PSS as injection layer for quantum dot light emitting diode

We report a color‐saturated, red quantum dot light‐emitting diode (QD‐LED) using graphene oxide doped PEDOT:PSS (PEDOT‐GO) as the hole injection layer (HTL) to optimize the band offset between the HTL and emitting layers. As the doping concentration of the GO increases, the valence band of the PEDOT‐GO down‐shifts by 0.66 eV approaching that of the QDs. Meanwhile, the conductivity and transparency linearly changes as the doping concentration of GO increases. The QD‐LEDs show a maximum luminance of up to 4200 cd/m², corresponding to 7.5 lm/W in power efficiency and a turn‐on voltage of 1.6 V. It is worth noting that the reduced turn‐on voltage can be attributed to the direct exciton recombination within the QDs. Overall, there is a sixfold enhancement in the performance of the QD‐LED with graphene oxide due to the higher hole injection/transfer rate and lower operating voltage.