Butterfly-Shaped Guest Molecules Enable Tunable Room-Temperature Phosphorescence in Host-Guest Doped Systems

Organic room-temperature phosphorescence (RTP) materials have attracted significant interest due to their potential in optoelectronics and anti-counterfeiting. However, achieving multicolor-tunable and long-lived RTP with simple, low-cost systems remains challenging. Herein, a facile host-guest doping strategy is developed to realize efficient and color-tunable RTP by embedding butterfly-shaped triphenylamine-based guest molecules (TPA, DBD, and DBDBD) into various host matrices (e.g., TPP, BPP, or CA). The doped crystals exhibit distinct afterglow colors (green to yellow) and prolonged long-persistent luminescence (LPL) (from 1 to 6 s of afterglow time) and phosphorescence lifetimes up to 763.33 ms, governed by host-guest energy transfer and intersystem crossing enhancement. Density functional theory (DFT) calculations reveal that the guest's electron-donating ability and the host's heavy-atom effect (e.g., P in TPP) synergistically promote charge separation and suppress non-radiative decay. Notably, DBDBD:TPP shows the longest LPL (6 s of afterglow time) due to optimal energy level alignment and strong intermolecular interactions. By leveraging the time- and color-dependent afterglow, applications in multilevel information encryption and anti-counterfeiting are demonstrated, where encrypted messages are dynamically revealed under UV excitation. This work provides a simple yet versatile approach to designing low-cost, multicolor RTP materials for advanced photonic applications.