Photoluminescence from lead halide perovskite superlattices

Lead halide perovskites are a new class of materials with promising optoelectronic properties. Bulk halide perovskites have been applied as solar cells, light-emitting diodes, photodetectors, and nanolasers. Colloidal lead halide perovskite nanocrystals have shown high quantum efficiency of photoluminescence. Moreover, perovskite nanocrystals can be assembled in an ordered 3D array or superlattice to demonstrate superfluorescence emission. In this work, we synthesized CsPbBr₃ superlattices with the linear size of several micrometers and studied their photoluminescence properties at room temperature and 6 K. We demonstrated that the photoluminescence spectra of  perovskite nanocrystals are preserved in superlattices at both temperatures. We also found a small spectral shift, which we attribute to a more uniformal size distribution of nanocrystals in the superlattice.