Efficient and color stable blue perovskite light-emitting diodes achieved via dual-additive phase modulation

non-radiative centers and promote small-sized nanocrystals, we optimize radiative recombination toward wide-bandgap phase distribution. This approach enables spectrally stable pure-blue electroluminescence at 474 nm without compromising photoluminescence quantum yield. Further hole-transport-layer engineering yields a peak external quantum efficiency of 4.6%, with spectral stability maintained under extreme bias up to 10.4 V. Our work provides critical insights into phase and halide management for high-performance blue PeLEDs, advancing their potential in full-color displays and lighting technologies.