Effect of the Host Lattice Environment on the Expression of 5s² Lone-Pair Electrons in a 0D Bismuth-Based Metal Halide

Abstract

ns 2 -Metal halide perovskites have attracted wide attention due to their fascinating photophysical properties. However, achieving high photoluminescence (PL) properties is still an enormous challenge, and the relationship between the lattice environment and ns 2 -electron expression is still elusive. Herein, an organic−inorganic Bi 3+based halide (C 5 H 14 N 2 ) 2 BiCl 6 •Cl•2H 2 O (C 5 H 14 N 2 2+ = doubly protonated 1-methylpiperazine) with a six-coordinated structure has been successfully prepared, which, however, exhibits inferior PL properties due to the chemically inert expression of Bi 3+ -6s 2 lone-pair electrons. After reasonably embedding Sb 3+ with 5s 2 electrons into the lattice of (C 5 H 14 N 2 ) 2 BiCl 6 •Cl•2H 2 O, the host lattice environment induces the Sb−Cl moiety to change from the original five-coordinated to six-coordinated structure, thereby resulting in a broad-band yellow emission with a PL efficiency up to 50.75%. By utilizing the host lattice of (C 5 H 14 N 2 ) 2 BiCl 6 •Cl•2H 2 O, the expression of Sb 3+ -5s 2 lone-pair electrons is improved and thus promotes the radiative recombination from the Sb 3+ -3 P 1 state, resulting in the enhanced PL efficiency. This work will provide an in-depth insight into the effect of the local structure on the expression of Sb 3+ -5s 2 lone-pair electrons.

Excitation-dependent efficient photoluminescence in an organic–inorganic (C4H12N)2HfCl6 perovskite induced by antimony doping

“…46 The temperature-dependent full width at half-maximum (FWHM) can be fit to determine the Huang–Rhys factor ( S ), which reflects the electron–phonon coupling strength. The following equation relates S and FWHM: 47,48 where ℏ ω phonon denotes the phonon frequency and k B denotes the Boltzmann constant. Fig.…”

Embedding Te4+ into Sn4+-Based Metal Halide To Passivate Structure Defects for High-Performance Light-Emitting Application

“… ,, Despite the poor optical activity, Sn­(IV)-based halides usually show excellent stability and remarkable photovoltaic properties, which render these materials promising for optoelectronic applications. Previous reports have shown that intentional doping of metal ions with active ns 2 lone pair may modulate the electronic environment of inert shells or passivate defects, thus altering materials’ PL properties. ,, Te 4+ shows a similar cationic radius and oxidation state to Sn 4+ , thus Te 4+ was expected to be embedded into the lattice of (C 4 H 7 N 2 ) 2 SnCl 6 to modulate its photophysical properties. As a result, Te 4+ -doped (C 4 H 7 N 2 ) 2 SnCl 6 were synthesized using the same method, which are flaky yellow crystals, suggesting the enhanced crystal quality and the change of band structures.…”

Turning Self‐Trapped Exciton Emission to Near‐Infrared Region in Thermochromism Zero‐Dimensional Hybrid Metal Halides

“…The non or weak PL of the two crystals might be ascribed to their electronic band structure (indirect bandgap, see the section below), which is widely observed in Bi‐based perovskite materials. [ 15 ] At 80 K, the PL of (DFPD) 2 CsBiI 6 crystals is enhanced without clear peak shift compared to that at room temperature. This indicates at the two different temperatures the PL processes are the same in terms of energy level.…”