Molecular Engineering through Control of Structural Deformation for Highly Efficient Ultralong Organic Phosphorescence

It is an enormous challenge to achieve highly efficient organic room‐temperature phosphorescence (RTP) with a long lifetime. We demonstrate that, by bridging the carbazole and halogenated phenyl ring with a methylene linker, RTP phosphors CzBX (X=Cl, Br) present high phosphorescence efficiency (ΦPh). A ΦPh up to 38 % was obtained for CzBBr with a lifetime of 220 ms, which is much higher than that of compounds CzPX (X=Cl, Br) with a C−N bond as a linker (ΦPh