Color and lifetime-tunable pure organic room-temperature phosphorescence via host–guest doping and Dexter energy transfer and its anti-counterfeiting applications

Abstract

Triplet–triplet energy transfer (TTET)-mediated room-temperature phosphorescent (RTP) materials have garnered considerable attention owing to their structural simplicity and robust luminescence stability. Nevertheless, their practical implementation is frequently impeded by solvent sensitivity and synthetic complexity. Critically, the absence of a comprehensive understanding of the underlying photophysical mechanisms hinders the rational design of high-stability RTP systems through targeted molecular selection. In this study, we present a facile fabrication strategy for BPSA@DMAP phosphorescent composites, achieving exceptional luminescence performance and extended lifetimes. This is accomplished by incorporating BPSA guest molecules-characterized by low spin–orbit coupling constants and electron-withdrawing properties-into DMAP host matrices possessing strong electron-donating capabilities and efficient intersystem crossing (ISC). The rigid crystalline environment of DMAP effectively suppresses non-radiative decay and oxygen quenching, thereby stabilizing triplet excitons. By fine-tuning molecular substituents and conjugation degrees, we successfully prolonged excited-state lifetimes and elucidated distinct emission profiles, encompassing tunable fluorescence, full-color phosphorescence, and a record phosphorescence lifetime of 979.1 ms. This work elucidates that the host matrix enhances guest ISC via the TTET mechanism and establishes a straightforward design paradigm for constructing efficient, stable luminescent materials with promising applications in information encryption and optical patterning.