Cover Picture: Neutral and Charged Exciton Fine Structure in Single Lead Halide Perovskite Nanocrystals Revealed by Magneto-optical Spectroscopy (Nanoletters 17(5), 2017)

The illustration shows the photoluminescence of individual perovskite CsPbBr3 nanocrystals at cryogenic temperature under magnetic fields. Two distinct spectral fingerprints (two/three color-emission) have been identified in the exciton recombination light, showing evidence for the existence of two crystalline structures, namely tetragonal D4h and orthorhombic D2h phases. Revealing the crystal structure of lead halide perovskite nanocrystals is essential for the optimization of stability of these emerging materials in applications such as solar cells, photodetectors, and light emitting devices.