Improving the Chemical Stability of Narrow-Band Green-Emitting Manganese(II) Hybrid by Zn-Doping.

Hybrid tetrahedral Mn(II)-based halides show great potential for narrow-band green emitters, which could be applied in the liquid crystal display field. However, the strategy to improve the chemical stability of tetrahedral Mn hybrids has not been fully investigated. Here, we demonstrate that Zn doping can be an effective route to significantly improve the stability of tetrahedral Mn hybrids under air conditions without compromising the luminous efficiency. A new bromide (ABI)2MnBr4 (ABI = 2-aminobenzimidazole) is synthesized, which exhibits a typical zero-dimensional structure with isolated [MnBr4]2- tetrahedra in the P1̅ space group. Under 450 nm excitation, a narrow-band green-emitting peak at 516 nm is observed with a full width at half maximum of 42 nm. It is indicated that spontaneous phase transition from the tetrahedral to octahedral motif occurs in this Mn hybrid driven by humidity, combined with the emission color change from green to red. Interestingly, this phase transition could be strongly suppressed by Zn doping with a very low doping amount (5%), leading to the significantly improved chemical stability of (ABI)2MnBr4 without reducing the photoluminescence quantum yield. Our work provides a simple and feasible strategy to enhance the chemical stability of the green-emitting (ABI)2MnBr4, and it may also be applicable for other tetrahedral Mn-based hybrids.