A novel group of N,N-diaryl-1,2-benzenediamine room temperature phosphors based on structural engineering

Abstract

Room temperature phosphorescence (RTP) has gained new momentum as a long-term topic along with the appearance of novel phosphors with versatile application potentials. Compared to traditional RTP materials, innovative pure organic phosphors have become promising alternatives due to their superiority in cost and processibility. However, the development of single-component organic phosphors with ultralong emission lifetimes and simple structures is still ongoing. Despite several kinds of organic phosphors being developed, the ones utilizing arylamine skeletons are barely reported. In this paper, we present a novel family of N,N-diaryl-1,2-benzenediamine phosphors with varying numbers of methyl substituents on terminal phenyl rings based on structural engineering. These molecules exhibited bright phosphorescence in the region of green to yellow light with a remarkably long lifetime up to 684 ms in crystalline states under ambient conditions. Comprehensive experimental and theoretical studies revealed that diverse intermolecular interactions and weak intramolecular hydrogen bonds co-contribute to the long-lived RTP emission. An encryption QR code was constructed, which displayed great potential in anti-counterfeiting applications. This work offered a novel structural motif for ultralong RTP material design and is constructive for material pool expansion.