Quantum-dot-based light-emitting diodes (QLEDs) are expected to play a key role in the next generation of electronic displays. Presently, the lifetime of quantum dots is significantly lower than required for commercial devices, and their efficiency is below the theoretical maximum.
In Advanced Functional Materials, Prof. Huaibin Shen, Prof. Lin Song Li, and their colleagues from Henan University and Northeast Normal University report the fabrication of a novel quantum dot for use in QLED displays.
One of the biggest problems in quantum-dot design is charge balance. There is often a large difference between the energy level of the valence band of quantum dots and the adjacent carrier transport layer. This leads to different rates of electron injection versus hole injection, leading to charge imbalances.
This novel quantum-dot design uses an intermediate zinc selenide layer and an ultrathin zinc sulfide outer layer. In addition, the surface of the quantum dot is modified with 2-ethylhexane-1-thiol. This molecule can dramatically improve the hole injection efficiency and thus lead to a more balanced charge injection.
This design gives rise to a red QLED that has the best efficiency and brightness ever recorded. In addition, its lifetime is estimated to be approximately 7300 hours, which is comparable to the best-reported red QLEDs.
To find out more about this new red QLED design, please visit the Advanced Functional Materials homepage.