Band Edge Energies and Excitonic Transition Probabilities of Colloidal CsPbX 3 (X = Cl, Br, I) Perovskite Nanocrystals

Colloidal CsPbX3 (X = Cl, Br, and I) nanocrystals have recently emerged as preferred materials for light-emitting diodes, along with opportunities for photovoltaic applications. Such applications rely on the nature of valence and conduction band edges and optical transitions across these edges. Here we elucidate how halide compositions control both of these correlated parameters of CsPbX3 nanocrystals. Cyclic voltammetry shows that the valence band maximum (VBM) shifts significantly to higher energies by 0.80 eV, from X = Cl to Br to I, whereas the shift in the conduction band minimum (CBM) is small (0.19 eV) but systematic. Halides contribute more to the VBM, but their contribution to the CBM is also not…

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  Science and Engineering Research Board

  Award: SR/S2/RJN-61/2012