Disrupting n-π* Transition of Benzophenone Derivatives’ T₁ States to Achieve Ultralong-Lived Room-Temperature Phosphorescence

Benzophenone, a well-known phosphorescence emitter, features near-unity intersystem crossing efficiency but shows a short phosphorescence lifetime of only 0.1–1 ms because of significant n-π* transition character in its T1 state. Here we report benzophenone derivatives that maintain high intersystem crossing efficiency and disrupt the n-π* transition's contribution to their T1 states, giving the emergence of a 2.0 s long phosphorescence lifetime under ambient conditions. Aromatic electron-donating substituents with low T1 energy levels are selected to build benzophenone derivatives. Consequently, the benzophenone derivatives' T1 states exhibit major localized excitation character from aromatic substituents and minor n-π* transition character. The modulation of electronic conjugation and dihedral angles between the benzophenone group and the aromatic substituent have been found to further disrupt the n-π* transition of the benzophenone derivatives' T1 states. After doping into rigid matrices, the resultant room-temperature phosphorescence materials display bright afterglow, exhibit excellent processability into diverse shapes, function as donors to form long-wavelength afterglow materials via energy transfer, and show aqueous dispersity enabled by emulsion polymerization and potential bioapplication.