Carrier recombination kinetics and dual-emission mechanism modulated via Sb3+ doping in zero-dimensional hybrid zinc halide

Zero-dimensional metal halides have attracted extensive attention as multifunctional optoelectronic materials and in radiation detection fields owing to their unique structural and luminescent properties. Herein, we take Sb3+-doped zero-dimensional hybrid zinc halide (C5H14N2)ZnCl4·H2O as the research object to systematically explore its crystal structure, carrier recombination kinetics, and exciton luminescence mechanisms. The results show that the introduction of Sb3+ can maintain the overall structural stability of the host lattice and significantly regulate the multi-channel radiative recombination pathways. This doped material displays characteristic dual-band luminescence with distinguishable carrier decay dynamics: the blue-green band originates from intrinsic band-edge self-trapped exciton recombination of the pristine matrix, whereas the near-infrared emission stems from characteristic inter-level carrier radiative transitions of Sb3+ dopants, accompanied by prolonged carrier lifetime and large Stokes shift. Temperature-dependent luminescence measurements uncover strong temperature dependence of the dual emission peaks in terms of carrier trapping/detrapping dynamics. The near-infrared luminescence presents prominent electron–phonon coupling, which reshapes carrier relaxation routes and induces an obvious spectral redshift. Density functional theory calculations further confirm that Sb3+ impurity introduces discrete mid-gap impurity states, enhances local orbital bonding interactions, and strengthens lattice rigidity and self-trapped exciton binding energy. These modifications optimize carrier localization, suppress non-radiative quenching channels, and ultimately facilitate efficient, stable radiative recombination of self-trapped excitons via regulated carrier transport and relaxation kinetics.