Medium-entropy perovskite quantum dots with both visible and infrared luminescence properties via solid-phase synthesis

In this study, a novel medium-entropy perovskite Cs(Pb 1/4 Yb 1/4 Mn 1/4 Ca 1/4 )Cl 3 quantum dots (QDs) were successfully synthesized via high-energy ball milling method. By introducing equimolar amounts of Mn 2+ , Yb 3+ and Ca 2+ cations, the lead content was reduced to 25%. This design of a medium-entropy structure not only preserves the fundamental perovskite lattice framework of CsPbCl 3 , but also introduces abundant intrinsic defects and localized structural distortions. The synthesized medium-entropy QDs exhibit unique dual-band luminescence properties at room temperature: a visible emission centered at ∼600 nm and a near-infrared (NIR) emission at ∼980 nm, attributed to the 4 T 1 → 6 A 1 transition of Mn 2+ and the f-f transition of Yb 3+ , respectively. The entropy-increasing strategy effectively suppresses non-radiative recombination, stabilizes the crystalline structure of the QDs, thereby significantly enhances both the luminescence properties and stability. Specifically, the QDs achieve a photoluminescence quantum yield (PLQY) of 13.22%, a visible fluorescence lifetime of 108.01 μs, and an outstanding NIR fluorescence lifetime of up to 2.20 ms. After 80 days of storage in ambient air at room temperature and atmospheric pressure, the QDs. still retain 77% and 86% of their initial visible and NIR luminescence intensities, respectively. This work provides a feasible new strategy for developing highly efficient and stable multispectral luminescent medium-entropy perovskite materials, expanding their application potential in biomedical and sensor fields.