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 (ΦPh3 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 longlived RTP materials with potential applications in anticounterfeiting or data encryption. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.