Quantum dot (QD) light-emitting diode (QLED) displays are highly promising optoelectronic devices, but several critical issues remain to be solved. The hole-electron charge balance is particularly important but hole-injection is more difficult than electron-injection in QLEDs; as a result, good hole injection ability is required. Here, we introduce a graphene oxide (GO) layer between the anode electrode and a typical hole injection layer of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) to improve the hole injection ability of a QLED device. The device with the GO/PEDOT:PSS bilayer hole injection layer exhibits a three-fold increase in brightness and external quantum efficiency as well as doubled current efficiency compared to a counterpart device using a single PEDOT:PSS layer. In addition, the turn-on voltage is improved from 8.35 V to 5.35 V. The dramatic improvements in the optoelectronic performance are attributed to the stepwise energy band structure in the hole injection bilayers; the work function of the GO layer is measured to be 4.98 eV, which reduces the interfacial barrier energy between the anode and PEDOT:PSS layer.
In this study, we report the high-brightness 1.53 inch 130 PPI active-matrix light-emitting diode display (AMLED). Dual gate coplanar amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor (TFT) is applied for the high brightness micro LED display. The micro LEDs optimized for the a-IGZO TFT backplane are fabricated, and the low-temperature eutectic bonding is applied to prevent thermal bonding damage. Finally, the glass based AMLED over ~ 10,000 cd/m² is demonstrated, using the dual gate coplanar a-IGZO TFT.
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