The effect of different halogen atoms on the rigid and energy transfer of organic cations

Low-dimensional organic-inorganic hybrid metal halides (OIMHs) have become an emerging class of light-emitting materials. Two zero-dimensional (0D) lead-free organic (EnrofloH₂)₄Mn₃X₁₂ (X = Cl, Br) has been reported in this work. Upon 338 and 340 nm excitation, (EnrofloH₂)₄Mn₃Cl₁₂·2Cl and (EnrofloH₂)₄Mn₃Br₁₂·2Br exhibit emission peaking at 460, 514 nm and 460, 520 nm respectively. It was noticed that the choice of the halide could profoundly govern the luminescent subjects (ENR or Mn²⁺) through the altered energy transfer. Different halogens could influence the rigidity of ENR organic cations by changing their stacking patterns and band gaps, thus manipulating their luminescent properties. The bandgap behaviors have been revealed by density functional theory calculations. Based on the results, the emission of both compounds come from organic cations (EnrofloH₂²⁺) and ⁴D-⁶A₁ transition of Mn²⁺ ions. The spectral interplay of these emission bands is governed by the temperature and the possibility of exchanging mechanisms between two emission centers.