Perovskite light-emitting diodes (PeLEDs) are an emerging technology that potentially offers tunable emission across the entire visible spectrum; low-temperature, solution-based processability; and narrowband light output for vivid color displays—all features currently lacking in commercial LEDs. Unfortunately, PeLEDs face a trade-off between efficiency and brightness, which has so far limited their practical application.

Now, however, a team led by Prof. YAO Hongbin, FAN Fengjia, LIN Yue, and HU Wei from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences—working with pure-red PeLEDs— has identified and addressed the root cause of PeLED efficiency loss at high brightness by introducing a novel material design that enables record-breaking device performance.

The associated study was published in Nature on May 7.

The researchers first used a self-developed diagnostic tool—electrically excited transient absorption (EETA) spectroscopy—to understand why the external quantum efficiency of PeLEDs based on three-dimensional (3D) mixed-halide perovskites like CsPbI3-xBrx plummets under high current densities. They found that hole leakage into the electron transport layer—previously undetected due to a lack of in situ characterization methods—was the primary culprit behind efficiency roll-off.

The researchers then engineered a 3D intragrain heterostructure within the perovskite emitter to enhance its carrier confinement capacity.  The heterostructure works by embedding narrow-bandgap light-emitting regions within a continuous 3D perovskite framework, interspersed with wide-bandgap barriers that confine the carriers. 

The molecule p-Toluenesulfonyl-L-arginine (PTLA), which bonds strongly to the perovskite lattice via multiple functional groups (guanidino, carboxyl, amino, and sulfonyl), is crucial to this strategy, as it expands the lattice locally and creates wide-bandgap phases without disrupting structural continuity. High-resolution transmission electron microscopy and ultrafast spectroscopy confirmed seamless carrier transfer between the heterostructure’s phases and suppressed hole leakage.

The optimized PeLEDs exhibited unprecedented performance and achieved a peak external quantum efficiency of 24.2% and a maximum luminance of 24,600 cd m-2—the brightest pure-red PeLED reported to date. Stability tests revealed a half-lifetime of 127 hours at 100 cd m-2, with minimal spectral shift during operation.

This work bridges a critical gap in perovskite optoelectronics, combining advanced diagnostics with innovative material engineering. Reviewers hailed the study as ”a landmark in perovskite LED research,” emphasizing its methodological rigor and transformative results.