Broadband emission originating from the stereochemical expression of 6s² lone pairs in two-dimensional lead bromide perovskites

Abstract

This work reports a new lead bromide hybrid featuring capped octahedral units. Comparative studies reveal the role of lone pair activity in governing local coordination geometry of the lead atom and broadband emission in 2D lead bromide perovskites.

Room-Temperature Ferroelectric Epitaxial Nanowire Arrays with Photoluminescence

“…50−53 As the lone pair activity increases, the inorganic lattice becomes softer and more vulnerable to interact with excitons. 50 This would facilitate strong electron−phonon coupling that leads to exciton self-trapping and the formation of broadband emission. 50,51 The room-temperature PL emissions for CsGeI 3 nanowires are less broad and more representative of bandgap emission.…”

“…50 This would facilitate strong electron−phonon coupling that leads to exciton self-trapping and the formation of broadband emission. 50,51 The room-temperature PL emissions for CsGeI 3 nanowires are less broad and more representative of bandgap emission. We also used fluorescence lifetime mapping to probe the carrier dynamics in the nanowires (Figure 2D,E).…”

“…The broad PL emissions observed in our CsGeBr 3 nanowires and bulk crystals are common in Ge-based halides, ,− thus making them promising candidates for broadband emitting materials. The stereochemically active ns 2 lone pair in metal cations has been hypothesized to play an important role in the broadband emission often observed in halide perovskites with off-centering distorted octahedra. − As the lone pair activity increases, the inorganic lattice becomes softer and more vulnerable to interact with excitons . This would facilitate strong electron–phonon coupling that leads to exciton self-trapping and the formation of broadband emission. , The room-temperature PL emissions for CsGeI 3 nanowires are less broad and more representative of bandgap emission.…”

“…The stereochemically active ns 2 lone pair in metal cations has been hypothesized to play an important role in the broadband emission often observed in halide perovskites with off-centering distorted octahedra. − As the lone pair activity increases, the inorganic lattice becomes softer and more vulnerable to interact with excitons . This would facilitate strong electron–phonon coupling that leads to exciton self-trapping and the formation of broadband emission. , The room-temperature PL emissions for CsGeI 3 nanowires are less broad and more representative of bandgap emission. We also used fluorescence lifetime mapping to probe the carrier dynamics in the nanowires (Figure D,E).…”