A research team from the University of Science and Technology of China (USTC) has made a major breakthrough in creating pure-red perovskite light-emitting diodes (PeLEDs) that shine brighter and more efficiently than ever before.
These new LEDs achieved a peak external quantum efficiency (EQE) of 24.2% and a maximum brightness of 24,600 cd m-2, setting a new record for pure-red PeLEDs.
This advancement could pave the way for more vivid displays and better lighting technologies.
For a long time, pure-red PeLEDs have faced a challenging trade-off: they could either be efficient or bright, but not both.
At high brightness, their efficiency would drop significantly, making it hard to use them for practical applications.
Scientists understood that part of the problem was linked to a phenomenon called carrier leakage, where electrical charges meant to produce light would escape, reducing the device’s overall efficiency.
However, the exact cause of this leakage remained a mystery—until now.
The research team, led by Professor Yao Hongbin and his colleagues Fan Fengjia, Lin Yue, and Hu Wei, used a special tool they developed called electrically excited transient absorption (EETA) spectroscopy.
This diagnostic tool allowed them to observe how electrical charges moved inside the LEDs in real time.
Through these observations, they discovered that the main reason for the efficiency loss was holes—one type of electrical charge—leaking into the electron transport layer of the device. This leakage had gone undetected before because there were no tools sensitive enough to catch it.
To solve this problem, the researchers created a new material design called a 3D intragrain heterostructure.
This design included narrow-bandgap light-emitting regions placed within a larger framework of the perovskite material, separated by wide-bandgap barriers. These barriers effectively trapped the electrical charges within the light-emitting regions, preventing them from leaking out.
A crucial part of this design was a molecule called p-Toluenesulfonyl-L-arginine (PTLA), which bonded tightly to the perovskite’s crystal structure.
PTLA not only kept the structure stable but also expanded the lattice locally, creating the necessary wide-bandgap regions without disrupting the overall material.
Using high-resolution imaging techniques, the researchers confirmed that this new structure allowed for smooth movement of electrical charges while keeping them confined to the light-emitting regions.
The results were impressive. The redesigned PeLEDs maintained high efficiency even at extremely bright levels—at 22,670 cd m-2, which is about 90% of their maximum brightness, the EQE stayed at 10.5%.
This was far better than any pure-red PeLED ever achieved before. The devices were also highly stable, with a half-lifetime of 127 hours at 100 cd m-2 and minimal color shifts during operation.
This breakthrough not only marks a major step forward in the development of perovskite LEDs but also opens up new possibilities for their use in ultra-bright displays and advanced lighting solutions.
The research team believes that their innovative design could change the way we think about LED technology, bringing more efficient and brighter displays to everyday life.
Reviewers of the study even called it “a landmark in perovskite LED research,” highlighting its potential to transform the field of optoelectronics.
