Organic-inorganic hybrid manganese bromine single crystal with dual-band photoluminescence from polaronic and bipolaronic excitons

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Organic molecule incorporation into inorganic halide brings up a series of variable optical physics and applications. Here, we report a new zero-dimensional Mn-based hybrid metal halide of C 4 H 14 N 2 MnBr 4 single crystals by using bi-amine group organic ions incorporation, which shows bright orange emission at room temperature. Interestingly, it exhibits unique dual-emission bands at 516 nm and 623 nm, both bands are related to the polaronic exciton or selftrapped exciton(STE1) and the bipolaronic exciton(STE2) due to the enhanced charged electron-phonon coupling by the incorporation of bi-amine-group molecular ions in the manganese halide lattice, which are also combined with the d-d transition of single Mn and Mn pair at a Mn-Mn distance close to a critical number of about 6.6 Å. This distance is found to be the critical distance between Mn ions for their paramagnetic and pair ferromagnetic phases in the manganese halides. The temperature-dependent photoluminescence (PL) spectra show that the C 4 H 14 N 2 MnBr 4 single crystals have a sensitive reversible thermo-induced PL characteristic, i.e., its orange and green PL colors can be converted back and forth through the temperature dependent electron-phonon coupling coefficient variations, during which there are different phase transitions. Dual emission C 4 H 14 N 2 MnBr 4 single crystals incorporated by a bi-amine molecules, exhibiting dual-emission bands reversible at 516 nm (green) and 623 nm (red) with scaling of electron-phonon coupling coefficients and structural transition at different temperatures, which is enhanced by the magnetic exchange of Mn ions. • Bulk C 4 H 14 N 2 MnBr 4 SCs were prepared out of MnBrx clusters array by a bi-amine molecule. • It give dual-emission bands at 516 nm and 623 nm with temperature variation. • The coexisting STE1 and STE2 states are related to the d-d transition of single Mn ion and FM coupled Mn ion pairs. • It shows a reversible thermo-induced PL color change due to a structural transition at varied temperatures.