Low-dimensional hybrid
organic–inorganic materials (HOIMs)
are being widely investigated for their unique optoelectronic properties.
Some of them exhibit broadband white-light (WL) luminescence upon
UV excitation, providing a potential for the fabrication of single-component
white-light-emitting diodes. Here, we report new examples of low-dimensional
HOIMs, based on 4-aminopyridinium (4AMP) and group 12 metals (Hg and
Zn), for single-component WL emission. The 4AMP cation containing
structures feature HgBr4 and ZnBr4 isolated
tetrahedra in (C5H7N2)2HgBr4·H2O (1) and (C5H7N2)2ZnBr4 (2), respectively. The presence of isolated molecular units
in the zero-dimensional structures results in strongly localized charges
and bright WL luminescence with corresponding Commission Internationale
de l’Eclairage color coordinates of (0.34, 0.38) and (0.25,
0.26), correlated color temperatures of 5206 K (1) and
11 630 K (2), and very high color rendering indexes
(CRI) of 87 (1) and 96 (2). The visibly
bright WL emission at room temperature is corroborated with high measured
photoluminescence quantum yield values of 14.87 and 19.18% for 1 and 2, respectively. Notably, the high CRI
values for these new HOIMs exceed the commercial requirements and
produce both “warm” and “cold” WL depending
on the metal used (Hg or Zn). Based on temperature- and powder-dependent
photoluminescence (PL), PL lifetimes measurements and density functional
theory calculations, the broadband WL emission is assigned to the
4AMP organic molecules emission and self-trapped states.