Lead cesium halide (CsPbX₃, X = Cl, Br, I) inorganic perovskite quantum dots (PeQDs) have received much attention due to their excellent photoelectric properties. Their optical properties can be regulated by quantum constraints, but the implementation of strong quantum constraints in PeQDs still faces great challenges, and there is still a lack of reliable methods to accurately control the PeQD size and luminescence performance.

In a study published in Chemical Engineering Journal, a research group led by LIU Xingyuan from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) proposed a new idea to synthesis ultra-small-size, highly efficient and stable CsPbBr₃ PeQDs.

Currently, the minimum size of CsPbBr₃ PeQDs with strong quantum confinement and unimodal photoluminescence (PL) spectrum is about 4 nm, showing a PL emission peak of 467 nm. However, the PL peak blue shift of pure CsPbBr₃ PeQDs is still a certain gap compared with that of chlorine-doped CsPbBr₃ PeQDs. Therefore, developing a reliable method to achieve ultra-strong quantum confinement of pure CsPbBr₃ PeQDs and adjust their PL peaks to the deep blue (< 450 nm) region is of great importance for resolving the negative effect of phase separation of chlorine-doped CsPbBr₃ PeQDs.

Researchers prepared Cs-DBSA solution by introducing DBSA coordination system, successfully realized the ultra-strong strong quantum confinement effect of CsPbBr₃ PeQDs, and prepared ultra-small size single-peak emission CsPbBr₃ PeQDs.

Moreover, the size of CsPbBr₃ PeQDs can be reduced with the increase of the amount of DBSA in the Cs-DBSA solution. The resulting CsPbBr₃ PeQDs has a minimum size of 1.8 nm, which is one of the smallest CsPbBr₃ PeQDs ever reported, the luminous peak is located at 448.8 nm and the luminous color is dark blue. The CsPbBr₃ PeQDs PLQY is up to 100% and has good stability.

The CsPbBr₃ PeQDs can be applied to enhance the cyan light region of white-light-emitting diodes (WLED) and achieve pure WLED with color coordinates of (0.32,0.33), which has an important application value for maintaining people's physical and mental health.