Molecular Engineering through Control of Structural Deformation for Highly Efficient Ultralong Organic Phosphorescence
Zheng Yin, Mingxing Gu, Huili Ma, Xueyan Jiang, Jiahuan Zhi, Yafei Wang, Huifang Yang, Weiguo Zhu, Zhongfu An
Abstract
Abstract 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 ( Φ Ph ). A Φ Ph 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 ( Φ Ph <1 %). Single‐crystal analysis and theoretical calculations revealed that, in the crystal phase, intermolecular π‐Br interactions accelerate the intersystem crossing process, while tetrahedron‐like structures induced by sp 3 methylene linkers restrain the nonradiative decay channel, leading to the high phosphorescence efficiency in CzBBr. This research paves a new road toward highly efficient and long‐lived RTP materials with potential applications in anti‐counterfeiting or data encryption.