Bright Yellow Electrogenerated Chemiluminescence Cell Using a Rubrene Solution Doped with an Emitting Assist Dopant

We demonstrated that the electrogenerated chemiluminescence (ECL) performances of 5,6,11,12-tetraphenyltetracene (rubrene)-based devices can be significantly enhanced by using an emitting assist dopant. We prepared an ECL solution by dissolving rubrene and 4-(di-p-tolylamino)-4′-[(di-p-tolylamino)styryl]stilbene (DPAVB) in an organic solvent. A microfluidic ECL cell having the prepared solution exhibited a bright yellow ECL emission from rubrene with a maximum luminance of 292 cd m−2 at 6.0 V and a maximum current efficiency of 4.50 cd A−1 at 5.5 V. Moreover, a current efficiency of over 3.0 cd A−1 was maintained from 3.0 to 6.5 V. Furthermore, the device lifetime was improved in comparison with the rubrene solution without DPAVB. The emission mechanism was discussed using cyclic voltammogram data. The DPAVB molecule was found to be more readily oxidized and more difficult to be reduced than rubrene. The excited rubrene molecules were expected to be produced efficiently in the device by the electron transfer reactions between rubrene•− and DPAVB•+ as well as rubrene•− and rubrene•+. Based on the findings, we concluded that the enhanced device characteristics were primarily attributed to the well-balanced generation of radical cations and anions.