Unusual phosphorescence of boric acid: From impurity or clusterization‐triggered emission?

Abstract

Abstract The unusual room‐temperature phosphorescence (RTP) from the n electron‐rich systems (without regular conjugated structure) has aroused great attention for structural designing and application development of RTP materials. Such emission has been ascribed to clusterization‐triggered emission (CTE) via weak through‐space conjugation of n electrons in the heteroatoms. However, there was suspicion on such RTP as impurity‐induced result. Therefore, in‐depth photophysical investigation and effective proof methods are needed to trace the origin of such RTP. Here, using the recently reported CTE phosphor boric acid as the example, a Jablonski diagram‐based verification protocol was proposed to confirm the intrinsic luminescence of the n electrons‐rich systems. Meanwhile, some other types of luminophores, that is, traditional phosphors, already reported impurity‐induced and host‐guest doping luminophores, were included for comparison. Overall, this work provides a basic paradigm for differentiating between the impurity‐involved and the n electron‐rich phosphors and will further deepen the understanding of nonconventional luminescence.