The exciton–phonon interaction as stimulated Raman scattering effect supported by the excitonic photoluminescence in BiI3 layered crystal structure

Exploring the synthesis, structure, and optoelectronic properties of lead-free halide perovskite Cs3Bi2I9 in single crystal and polycrystalline forms

“…The Raman spectra that correspond to the Cs 3 Bi 2 I 9 perovskite single crystal and Cs 3 Bi 2 I 9 perovskite thin film are shown in figures 13(a) and (b), respectively. The Raman characteristics peaks observed at 63 cm −1 , 89 cm −1 , 102 cm −1 , 135 cm −1 , and 152 cm −1 showed the crystalline nature of the Cs 3 Bi 2 I 9 perovskite single crystal [70] and the function of Bi-I bonds in the crystal's optical qualities [71]. The vibration of [Bi 2 I 9 ] 3 − anions within the crystal structure serves as the primary source of various vibrational modes observed in the Cs 3 Bi 2 I 9 crystal lattice with a space group of P63/mmc.…”

Photoinduced coherent modulation of an excitonic resonance via coupling with coherent optical phonons

“…Such large binding energy in a bulk semiconductor is a rather unique feature. Resonant Raman scattering combined with luminescence [26][27][28] have identified an interaction between excitons and the main A g vibrational mode at 3.4 THz (113 cm −1 ) [29]. More recently, transient absorption of spin-coated thin films of BiI 3 suggested that coherent optical phonons and excitons should be coupled in the ultrafast time domain [30].…”