Solution Processing Small-Molecule Organic Emitter in Field-Induced, Carrier Gated Lighting Devices

With the significant advantages of low-cost manufacturing and large device area, field-induced alternating current organic electroluminescent (AC-OEL) devices based on solution processed polymeric emitters have been intensively stuided over the past few years. However, the choice of polymeric emitter for full color devices is restricted when compared to organic small molecules emitters. The thermal evaporation of organic small molecules has critical drawbacks as a fabrication technique such as high vacuum manufacturing cost and being time consuming. In this work, state-of-the-art solution processed small-molecule films are fabricated and compared to their vacuum-deposited counterpart. The proper solvent for tris(8-hydroxyquinolinato) aluminum (Alq(3)) is studied, which has an adequate solubility but also avoids the interfacial mixing between top emission layer and bottom hole generation layer (HGL). Comprehensive nongated and ZnO-gated AC-OEL devices based on Alq3 emitter are fabricated and the underlying mechanism of hole carrier manipulation at ZnO/HGL interfaces is investigated in time-resolved current and voltage characteristics.