Upconversion and multiexciton generation in organic Mn(ii) complex boost the quantum yield to > 100%

Organic–inorganic hybrid, green light-emitting single crystals of [Me 3 NPh] 2 MnBr 4 (1) (Ph: phenyl) are synthesized and exhibit both upconversion and multiple exciton generation leading to a photoluminescence quantum yield of 189%.