Shanghai Institute of Optics and mechanics has made progress in the research of

Recently, researcher donghongxing and researcher Zhang long from the laser and infrared materials laboratory of Shanghai Institute of Optics and precision machinery, Chinese Academy of sciences have made progress. They have obtained stable multi wavelength laser in a single halogen graded all inorganic perovskite superlattice structure through ion exchange. Relevant research results were published on advanced optical materials under the title of "stable multi-wavelength finishing in single perovskite quantum dot superlattice".

Multi wavelength micro nano lasers have important application prospects in highly integrated photonic devices. However, because all inorganic perovskite has dynamic soft ion lattice and low halide anion migration energy, it is still a challenge to obtain alloy micro nano perovskite structure with gradual band gap. Even if the halogen doped perovskite micro nano structure with gradual band gap is obtained by complex means, the ion migration will occur due to the existence of halogen concentration gradient, resulting in the instability of the band gap gradient.

Fig. 1 (a) schematic diagram of ion exchange in superlattice; (b) Schematic diagram of polychromatic micro nano laser in graded superlattice; (c) Multi wavelength tunable lasing in graded superlattices.

In order to solve the above problems, researchers proposed an alloy superlattice structure with stable band gap gradient through fine ion exchange in perovskite quantum dot superlattice. Quantum dot superlattice is a long-range ordered and densely arranged array of quantum dots, in which the adjacent quantum dots have a certain distance. This discrete arrangement of quantum dots in the superlattice can increase the energy barrier of anion migration, which is conducive to the formation of stable band gap difference between various regions in the superlattice after ion exchange. The photoluminescence spectra confirmed that the band gap gradient stability of the obtained band gap graded cspbbr3-3xcl3x alloy superlattice was about 10 times higher than that of the perovskite single crystal alloy nanowires. The mechanism of ion exchange in the superlattice is analyzed by combining fluorescence spectra and density functional theory. Based on the alloy superlattice structure, a stable multi wavelength laser output is achieved.

Source: Shanghai Institute of Optics and mechanics, Chinese Academy of Sciences