Stable Multi‐Wavelength Lasing in Single Perovskite Quantum Dot Superlattice.

Single perovskite alloy micro‐nano structure capable of emitting multi‐wavelength tunable lasing is desirable for its potential application in highly integrated photonic devices. However, owing to the soft and dynamic crystal lattice of perovskite and the low mobility energy of halide anion, it is still a challenge to obtain alloy micro‐nano structures with a stable bandgap gradient. Herein, based on the highly ordered superlattice consisting of well‐separated individual quantum dots and precise anion exchange strategy, a single perovskite alloy superlattice is obtained with a widely tunable bandgap. The photoluminescence (PL) spectra results indicate that the stability of the bandgap difference of the alloy superlattice sample is approximately 10 times higher than that of the previously reported perovskite single‐crystal alloy nanowires. By combination of quantitative study based on confocal PL measurements and theoretical calculations, the kinetics and atomic‐scale anion exchange mechanism are analyzed, the latter being responsible for the formation of stable bandgap gradient in the alloy superlattice. Multi‐wavelength lasing is further realized in single alloy superlattice. In addition, carrier transportation dynamics reveals the energy‐transfer process in the alloy superlattice, explaining the difficulties of realizing multicolor lasing. The work provides a new approach to solving problems in the field of stable multicolor microlasers. [ABSTRACT FROM AUTHOR]