Pure Blue Perovskites Nanocrystals in Glass: Ultrafast Laser Direct Writing and Bandgap Tuning

Chemical engineering in lead halide perovskite nanocrystals (PNCs) has garnered significant attention for tailoring optoelectronic properties, such as bandgap, quantum yield (QY), and stability. Here, pure blue emissive PNCs in glass by using ultrafast laser are reported. The emission wavelength is tuned in the range from 461 to 520 nm by engineering the chemical composition in the B‐site Cd/Pb mix‐cation system. The photoluminescence (PL) QY of CsCdxPb1−xBr3 PNCs reaches 13.4% for the pure blue emission at 467 nm, which is twice that of CsPbBryCl3−y PNCs. The pure blue emissive PNCs exhibit remarkable stability when exposed to ultraviolet (UV) radiation, heat, and ethanol solvents. The ultrafast laser print patterns can be encrypted and decrypted for information, which shows great potential for crucial information security applications. These results imply that B‐site engineering for lead halide PNCs embedded in glass is effective to tailor the PL spectra and increase the PL QY. The pure blue emissive PNCs hold great potential in the applications of blue and full‐color emissive devices. Ultrafast lasers can induce bandgap tuning by engineering B‐site cations of pure blue perovskites nanocrystals (PNCs) in Cd/Pb mixed glass. With manipulation of ultrafast laser‐induced liquid nanophase separation, the Cd/Pb cation concentration in the forming PNCs can be controlled at the nanoscale, and the emission wavelength of CsCdxPb1−xBr3 PNCs can be tuned within the range of 461–520 nm.