Modified Charge Injection in Green InP Quantum Dot Light-Emitting Diodes Utilizing a Plasma-Enhanced NiO Buffer Layer
Lishuang Wang, Zhen Fan, Danyang Liu, Zhaobin Zhang, Bingsuo Zou
Abstract
With the growing concern for green and environmentally friendly quantum dots (QDs), the investigation of low-toxicity heavy-metal-free light-emitting materials and devices has become a research hotspot. Due to their high quantum yield, tunable emission, and environmentally friendly properties, the low-toxicity III–V InP quantum dot light-emitting devices (QLEDs) have great application potential in next-generation full-color displays and lighting. In this work, charge injection in high-performance green InP QLEDs was modified by using a low-temperature atomic layer-deposited (ALD) nickel oxide (NiO) buffer layer. The device with the NiO buffer layer effectively suppressed the nonradiative recombination process and enhanced the hole injection, exhibiting a 1.35-fold enhanced external quantum efficiency (EQE). Moreover, different oxygen plasma-enhanced conditions were applied to the deposition of the NiO film. As the ambient oxygen flux increased (50–200 sccm), Ni 2+ and interstitial oxygen vacancies were generated within the NiO film, which effectively improved the hole injection and promoted the carrier balance injection. The best-performing device with a 100 sccm O 2 –NiO film realized a 2.36 times higher EQE (6.75%) than the device without the NiO buffer layer, with a maximum current efficiency (CE) of 12.73 cd/A. The experimental results provide an effective strategy to further improve the charge balance and performance of InP-based QLEDs