N-Annulated Perylene Diimide Emitters for High-Performance Peroxyoxalate/H₂O₂ Chemiluminescence

Perylene diimides (PDIs), as one type of the most promising luminescent materials, have been attracted much attention. Herein, chemiluminescent (CL) properties of two N-annulated PDI dimers with hexyl linear alkyl chains (PDI-1) and 2,4,6-trimethylbenzyl sidechains (PDI-2) at the pyrrolic N-positions were investigated. CL emissions are explored in chemical reactions with bis(2-carbopentyloxy-3,5,6-trichlorophenyl) oxalate (CPPO) and hydrogen peroxide (H₂O₂). Spooling CL spectroscopy was utilized for investigating their CL reaction mechanism, illuminant decay and absolute efficiencies. CL emission peak wavelength of PDI-1 or PDI-2 is similar to their photoluminescence (PL) one, demonstrating emissions mainly from the monomeric excited state in the absence of surface states. Moreover, absolute irradiance measurements on a set of a spectrograph and CCD camera or an Ocean Insight spectrometer along with a 6-inch integrating sphere were calibrated using a standardized light source for further quantum efficiency determinations. The absolute CL efficiency of PDI-1 (3.57% ± 0.03%) was discovered to be 6 times higher than that of PDI-2 (0.603% ± 0.001%). The absolute CL efficiencies of PDI-1 and PDI-2 are superior to those of many other organic molecules and graphene quantum dots. This work provides a novel pathway for the exploration of these PDI materials to improve their CL performance.