Laser-driven anion exchange for precise composition control in perovskite materials with tunable optical properties.

Perovskite quantum dots (QDs) have attracted great attention due to their tunable bandgap and emission wavelength, which can be adjusted by simply modifying the halide composition. However, it is still a challenge to achieve precise control of the composition of perovskite QDs due to the rapid and uncontrollable reactions. Herein, a laser-driven anion exchange method is developed to achieve precise control on the composition of perovskite QDs and optical properties. By adjusting the laser power density, the emission wavelength of the films can be continuously tuned from 414 to 648 nm. Sandwich and heterojunction structures are successfully fabricated by controlling the position of the laser spot irradiation. Furthermore, this method can fabricate films with a smooth, dense particle surface morphology, which provides potential applications in fields such as full-color displays and solar cells. The long-term stability of perovskite QDs films is achieved by using encapsulation technology, with excellent optical stability even after 50 days of immersion in water.