BTD-FL was selected as the preferred HLCT system due to its moderate dihedral angle and appropriate donor [9,9-dimethyl-9H-fluoren (FL)] and acceptor [benzothiadiazole (BTD)] strength, which exhibits partial HOMO-LUMO separations and distinct HLCT characters (Fig. ). Introducing bromine atoms into BTD-FL to improve SOC and absorption cross-section, resulting in BTD-FLBr. radiative decay, the nonconjugated alkyl bromides were introduced into BTD-FL to obtain BTD-HeBr. These three HLCT emitters can be easily synthesized by one-pot method with a high reaction yield under the same reaction conditions by using different substituted reactants (Supplementary Fig. ).