Highly efficient and stable deep-blue room temperature phosphorescence via through-space conjugation

Efficient blue and deep-blue room temperature phosphorescence (RTP) is still a great challenge due to the difficulties in populating and stabilizing the excitons in relatively high-lying states. Inorganic boric acid, lacking conventional luminophores in its structure, is generally not considered as efficient material for RTP. In this work, we illustrated how to make deep-blue RTP materials with both high emission efficiency (phosphorescence quantum yield of 45%) and an ultralong lifetime (2.9 s) through a heat treatment strategy. Moreover, a throughspace conjugation assisted energy transfer and rigidification mechanism was proposed for explaining the simultaneous promoting of emission lifetime and efficiency. In addition, the deep-blue RTP materials displayed excellent stability against restrict external environments (such as high concentration acid, alkali, oxidant, reductant and organic solvents). Benefiting from these high-performance RTP materials, multi-level information encryption under harsh conditions was demonstrated. The research results thus provide a universal principle and strategy for designing stable and efficient blue RTP materials, which also extend their applications in various environments.

Automated summary

This study successfully developed efficient and stable deep-blue phosphorescent materials through a heat treatment method and proposed an energy transfer and rigidification mechanism to explain their high emission lifetime and efficiency. These materials demonstrated excellent stability in various harsh environments and can be used for multi-level information encryption.