Novel material design enables pure-red perovskite LEDs with record-breaking performance

A team from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) has resolved a critical challenge in pure-red perovskite light-emitting diodes (PeLEDs) by identifying and addressing the root cause of efficiency loss at high brightness.

Published in Nature, their study introduces a novel material design that enables record-breaking device performance, achieving a peak external quantum efficiency (EQE) of 24.2% and a maximum luminance of 24,600 cd m^-2—the brightest pure-red PeLED reported to date.

Pure-red PeLEDs, crucial for vivid displays and lighting, have long faced a trade-off between efficiency and brightness. While 3D mixed-halide perovskites like CsPbI_3-xBr_x offer excellent charge transport, their efficiency plummets under high current due to unresolved carrier leakage.

Using a self-developed diagnostic tool called electrically excited transient absorption (EETA) spectroscopy, the team, led by Prof. Yao Hongbin, Fan Fengjia, Lin Yue, and Hu Wei, captured real-time carrier dynamics in operating devices. They discovered 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.

To tackle this, the researchers engineered a 3D intragrain heterostructure within the perovskite emitter. This design embeds narrow-bandgap light-emitting regions within a continuous [PbX₆]^4- framework, separated by wide-bandgap barriers that confine carriers.

Key to the strategy is the molecule p-Toluenesulfonyl-L-arginine (PTLA), which bonds strongly to the perovskite lattice via multiple functional groups (guanidino, carboxyl, amino, and sulfonyl).

PTLA expanded the lattice locally, creating wide-bandgap phases without disrupting structural continuity. High-resolution TEM and ultrafast spectroscopy confirmed seamless carrier transfer between the heterostructure’s phases and suppressed hole leakage.

The optimized PeLEDs exhibited unprecedented performance: at 22,670 cd m^-2—nearly 90% of peak brightness—the EQE remained at 10.5%, far surpassing previous records. Stability tests revealed a half-lifetime of 127 hours at 100 cd m^-2, with minimal spectral shift during operation.

The team attributed this success to the heterostructure’s dual role: confining holes to the emitter while maintaining high carrier mobility through an uninterrupted 3D lattice.

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.