Cation−π Interaction Induced Excimer Formation: A New Strategy for High‐Efficiency Organic Solid‐State Luminescence

Abstract Organic solid‐state luminescence materials have shown great promise in many forefront areas of modern chemistry. However, the well‐developed organic luminescent solids usually provoke a mass of synthetic steps. To better utilize their performances, the development of simple strategies for host materials is a goal of general concern. Herein, a series of highly efficient solid‐state luminescence materials are attained with aid of one‐step acidification of commercially available molecules. The mechanism demonstrates that the luminous efficiency of the solid‐state molecules is efficiently improved due to the synergy from the emergence of cation–π interaction and the formation of excimer. The cation–π interaction replaces π–π packing, leading to the formation of dimers with higher rigidity in solid state accompanied by red‐shifted emissions. Therefore, this one‐step acidification design concept will light the great passion of scientists for the fabrication of cation−π‐triggered analogous organic solid‐state luminescence materials with different colors by changing the substituents on benzene moieties.