Researchers have developed perovskite light-emitting diodes (pLEDs) with an external quantum efficiency (EQE) exceeding 20%, a significant advancement in optoelectronic devices. The breakthrough was achieved through a novel compositional distribution strategy that enhances both luminescence and charge injection balance. By mixing pre-synthesized CsPbBr3 perovskite with MABr additive in the precursor, a quasi-core-shell structure is formed, which passivates non-radiative defects and improves photoluminescence quantum yield (PLQY). This structure enables efficient charge injection and results in pLEDs with an EQE of 20.3%, marking a major step toward practical commercialization of pLEDs for lighting and display applications. The study highlights the importance of optimizing perovskite film quality and charge injection balance to achieve high performance. The researchers used a one-step deposition method to fabricate a compositionally-graded perovskite layer, which consists of a defect-passivated perovskite layer and an electrical passivating layer. This approach led to a significant improvement in device efficiency, with the best-performing pLED achieving an EQE of 20.3% and a maximum current efficiency of 23 cd·A⁻¹ at 3.8 V. The study also demonstrates the stability of the pLEDs, with a half-lifetime (T50) of ~10 min at 100 cd m⁻² and continuous operation for ~46 hours at a constant luminance of ~100 cd m⁻². These results indicate that the pLEDs are highly stable and suitable for practical applications. The researchers emphasize that further improvements in device stability can be achieved through the suppression of ion migration, fabrication of high-quality perovskite layers, and optimization of the perovskite/ETL and perovskite/HTL interfaces. The high EQE of these devices is now on par with more mature technologies such as OLEDs, making perovskite-based LEDs a promising candidate for future lighting and display technologies.Researchers have developed perovskite light-emitting diodes (pLEDs) with an external quantum efficiency (EQE) exceeding 20%, a significant advancement in optoelectronic devices. The breakthrough was achieved through a novel compositional distribution strategy that enhances both luminescence and charge injection balance. By mixing pre-synthesized CsPbBr3 perovskite with MABr additive in the precursor, a quasi-core-shell structure is formed, which passivates non-radiative defects and improves photoluminescence quantum yield (PLQY). This structure enables efficient charge injection and results in pLEDs with an EQE of 20.3%, marking a major step toward practical commercialization of pLEDs for lighting and display applications. The study highlights the importance of optimizing perovskite film quality and charge injection balance to achieve high performance. The researchers used a one-step deposition method to fabricate a compositionally-graded perovskite layer, which consists of a defect-passivated perovskite layer and an electrical passivating layer. This approach led to a significant improvement in device efficiency, with the best-performing pLED achieving an EQE of 20.3% and a maximum current efficiency of 23 cd·A⁻¹ at 3.8 V. The study also demonstrates the stability of the pLEDs, with a half-lifetime (T50) of ~10 min at 100 cd m⁻² and continuous operation for ~46 hours at a constant luminance of ~100 cd m⁻². These results indicate that the pLEDs are highly stable and suitable for practical applications. The researchers emphasize that further improvements in device stability can be achieved through the suppression of ion migration, fabrication of high-quality perovskite layers, and optimization of the perovskite/ETL and perovskite/HTL interfaces. The high EQE of these devices is now on par with more mature technologies such as OLEDs, making perovskite-based LEDs a promising candidate for future lighting and display technologies.