• second-order Raman scattering;
  • triple resonance;
  • perovskite semiconductor CsSnI3

We report on the first-order and second-order Raman scattering (SORS) by longitudinal optical (LO) phonons in perovskite semiconductor CsSnI3. The intensity of SORS is stronger than that of the first order. The spectral line shape of SORS is asymmetric and much broader than that of the first order. It is identified that the strong SORS intensity is attributable to the triply enhanced resonant process, which is naturally implemented through the peculiar band structure of this semiconductor compound having two adjacent parallel conduction bands with a separation close to the energy of two LO phonons. Copyright © 2012 John Wiley & Sons, Ltd.