Unprecedentedly, cesium lead halide (CsPbX₃, X = Cl, Br, I) quantum dots (QDs) with tunable spectral emissions and photophysical properties are used as a common emissive material for the fabrication of full-color perovskite QDs light-emitting diodes. An efficient, non-destructive ligand/anion exchange strategy is developed to fine-tune the optical properties of CsPbBr₃ QDs solid-state films. Specifically, the surface of the CsPbBr₃ QDs films is passivated by phenethylammonium halides, PEAX (X = Cl, Br, I) salts via a facile spin-coating technique, producing PEAX-CsPbBr₃ QDs (X = Cl, Br, I) films with tunable (blue/green/red) color emissions that cover the entire visible spectrum. During passivation treatment, the PEAX passivators supply additional halide (Cl, Br, I) anions to fill in the intrinsic Br vacancies, allowing contemporary defect-passivation and emission-tuning effect in the QDs film. More importantly, this surface passivation strategy enables the fabrication of full-color perovskite QDs light-emitting diodes using PEAX-CsPbBr₃ QDs as a common emissive film.

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