Electron-Transport Properties and Use in Organic Light-Emitting Diodes of a Bis(dioxaborine)fluorene Derivative

Bis(dioxaborine)fluorenes (DOB) have been studied as potential electron-transport materials. These materials are reversibly reduced at ca. −1.31 V vs ferrocenium/ferrocene, indicating that they have considerably higher electron affinities than tris(8-hydroxyquinoline)aluminum (AlQ3). They are also highly fluorescent in both solution and the solid state. Time-of-flight measurements show the room-temperature electron mobility of one example to be 2 orders of magnitude higher than the commonly used electron-transport material AlQ3. Organic light emitting diode (OLED) devices based on the dioxaborine and poly(9-vinylcarbazole) have been fabricated and show a red emission that can be attributed to an exciplex or a charge-transfer complex formed between the two organic components. Förster energy transfer from the exciplex or the charge-transfer complex to a phthalocyanine dopant in the dioxaborine electron-transport layer leads to a near-infrared-emitting OLED.