Efficient photo-induced RTP materials based on phenothiazine and polycyclic aromatic hydrocarbons: Tunable emission color and thermal stimulus response

Abstract

The development of photo-responsive room temperature phosphorescence (RTP) materials has attracted more and more attention for their broad application prospects. Until now, it is still difficult to obtain the related materials with both high efficiency and long lifetime. And the lacking of emission in blue and red regions also largely restricts their further applications. In this work, we reported a new strategy to maintain both high efficiency and long lifetime in RTP luminogens through the integration of phenothiazine to facilitate n-π^⋆ transition and polycyclic aromatic hydrocarbons (PAHs) dominated by π-π^⋆ transition. When they were doped into polymer matrix, full color photo-induced RTP materials were obtained for the changed π-conjugation of PAHs. Among them, PTri@PVP showed the best RTP performance with phosphorescence efficiency of 20.73% and lifetime up to 819 ms. Specifically, after turning off the ultraviolet-visible (UV) irradiation upon this system, time-dependent phosphorescence afterglow from green to blue was exhibited, which was found to originate from two distinct molecular conformations and could be further regulated by thermal stimulus. Accordingly, multiple anti-counterfeiting applications, including screen printing, multi-color patterns and multi-dimensional information encryption, were successfully demonstrated.