Ultralong sodium alginate-based room temperature phosphorescence materials with advantages of color tunability, flexibility and facile large-area fabrication

Organic room temperature phosphorescence (RTP) has promising applications in diverse fields, whereas a formidable challenge remains in the development of flexible organic RTP materials, especially environmentally friendly RTP materials. In this work, natural polymer sodium alginate (SA)-based RTP materials have been facilely developed by doping phenylboronic acid (PBA) and its derivatives into SA matrices. 4-carboxyphenylboric acid doped system SA-CPBA exhibits the best RTP performance with an ultralong phosphorescence lifetime of up to 231 ms. Interestingly, SA-CPBA shows excitation-dependent phosphorescence color tunability by water vapor fumigation and heating, and the afterglow color change has good reversibility upon alternating treatment of water vapor fumigation and heating. Amazingly, flexible and transparent RTP films are obtained through adding a certain amount of glycerol (G) into SA-CPBA matrices, and SA-CPBA-G also possesses excellent excitation-dependent phosphorescence color tunability. Furthermore, the flexible SA-CPBA-G film can be conveniently fabricated on a large area. These excellent features enable the prepared SA-based RTP materials to be successfully applied in the fields of flexible display and information encryption. This work provides a guideline for the preparation of environmentally friendly flexible polymer-based color-tunable RTP materials and expands the application range of SA-based materials to the field of flexible displays.