Spectrally
stable pure-red perovskite quantum dots (QDs) with low
lead content are essential for high-definition displays but are difficult
to synthesize due to QD self-purification. Here, we make use of entropy-driven
quantum-confined pure-red perovskite QDs to fabricate light-emitting
diodes (LEDs) that have low toxicity and are efficient and spectrum-stable.
Based on experimental data and first-principles calculations, multiple
element alloying results in a 60% reduction in lead content while
improving QD entropy to promote crystal stability. Entropy-driven
QDs exhibit photoluminescence with 100% quantum yields and single-exponential
decay lifetimes without alteration of their morphology or crystal
structure. The pure-red LEDs utilizing entropy-driven QDs have spectrally
stable electroluminescence, achieving a brightness of 4932 cd/m2, a maximum external quantum efficiency of over 20%, and a
15-fold longer operational lifetime than the CsPbI3 QD-based
LEDs. These achievements demonstrate that entropy-driven QDs can mitigate
local compositional heterogeneity and ion migration.