Low-dimensional
Bi/Sb-based organic–inorganic metal halides
(OIMHs) have attracted immense attention from the research community
because of their structural diversity and efficient luminescence properties.
Further understanding of the relationship between the structure and
luminescence properties of these materials is of utmost importance
for tuning the luminescence properties for various practical applications.
Herein, we have synthesized two lead-free Bi/Sb-based novel OIMHs,
(3,5-DMP)2BiCl5 and (3,5-DMP)2SbCl5 [(3,5-DMP) = 3,5-dimethylpiperidine], with zero-dimensional
(0D) structures and crystallizing in triclinic (P
space
group) and monoclinic (P21/c space group) crystal systems, respectively.
Both the compounds behave as typical semiconductors with indirect
optical band gaps of 3.34 and 3.36 eV for pristine Bi and Sb compounds.
These compounds exhibit higher environmental and thermal stability
at ambient conditions. Gradual substitution of Sb at the Bi site in
(3,5-DMP)2Bi1–x
Sb
x
Cl5 resulted in the introduction
of structural strain due to the significant expression of the lone
pair effect, thus leading to a structural transition from the triclinic
to monoclinic phase. The effect of the structural phase transition
on the optical properties is also studied in (3,5-DMP)2Bi1–x
Sb
x
Cl5. This work may offer new direction and guidance for
exploring various 0D hybrid metal halides and tuning the structures
for improvement in the luminescence properties.