Ultralong room-temperature phosphorescence from polycyclic aromatic hydrocarbons by accelerating intersystem crossing within a rigid polymer network

Abstract

Polymer-based room temperature phosphorescence has attracted great attention for potential applications in organic light-emitting diodes, sensors, data encryption, and anti-counterfeiting. One of the most applied strategies to realize efficient room-temperature phosphorescence (RTP) is to suppress the non-radiative transition by introducing secondary interactions (hydrogen bonding, ionic bonding, etc.) between phosphors and the polymer matrix. However, water and moisture will turn off the phosphorescence emission by damaging the hydrogen bonding network. Besides, the role of the polymer matrix in the photophysical process is still unknown. Herein, we successfully achieve robust long-lived room temperature phosphorescence materials based on purely polycyclic aromatic hydrocarbons (PAHs) by in situ doping with a rigid polymer network during polymerization. The materials exhibited an ultralong phosphorescence lifetime of up to 1.27 s, a large Stokes shift of 233 nm and a remarkable duration of afterglow for over 12 s, which are extremely stable even under aqueous conditions. Photophysical analysis and transient absorption spectroscopy reveal that phosphorescence is facilitated by accelerating the intersystem crossing (ISC) from singlet to triplet states and suppressing the non-radiative transition of the triplet excitons within the rigid polymer matrix. Furthermore, 3D phosphorescent structures and 2D large-scale, transparent displays with re-writable encoded information are fabricated with the facilely processed PAHs@polymer RTP materials.