Physics

Nanotechnology

Organic chemistry

Crystallization

Triphenylphosphine oxide

Catalysis

Excited state

Phosphorescence

Nuclear physics

Chemistry

Materials science

Triphenylphosphine

Singlet state

Quantum mechanics

Optoelectronics

Doping

Intersystem crossing

Fluorescence

Angewandte Chemie International Edition

Compared with inorganic long‐lasting luminescent materials, organic room temperature phosphorescent (RTP) ones show several advantages, such as flexibility, transparency, solubility and color adjustability. However, organic RTP materials close to commercialization are still to be developed. In this work, we developed a new host–guest doping system with stimulus‐responsive RTP characteristics, in which triphenylphosphine oxide ( OPph 3 ) acted host and benzo(dibenzo)phenothiazine dioxide derivatives as guests. Turn‐on RTP effect was realized by mixing them together through co‐crystallization or grinding, in which the efficient energy transfer from host to guest and the strong intersystem crossing (ISC) ability of the guest have played significant role. Further on, multistage stimulus‐responsive RTP characteristics from grinding to chemical stimulus were achieved via introducing pyridine group into the guest molecule. In addition, the anti‐counterfeiting printings were realized for these materials through various methods, including stylus printing, thermal printing and inkjet printing, which brings RTP materials closer to commercialization.

Multistage Stimulus‐Responsive Room Temperature Phosphorescence Based on Host–Guest Doping Systems