Ultrasonic Spray Coating OLEDs

The positive reactions in the consuming market signify that organic light-emitting devices (OLEDs) would be likely to become the next generation display and lighting technology in the future. Nevertheless, the high manufacture cost is still an important factor that hinders further development of the OLED industrialization before the OLED products become the mainstream in display and lighting area. At present, the common used fabrication process for OLEDs is the vacuum thermal evaporation process, which should assume the primary responsibility to the high manufacture costs. Thus, to reduce the manufacture costs, solution processes which are simple and require no complicated instruments, especially spin coating process, have been proposed to fabricate OLEDs. However, although spin coating has been proved to be a useful experimental technique in laboratory, its disadvantages, such as the low material utilization, the incompatibility with streamline production and a strict requirement to the viscidity of solution, are still evident. In generally, the small molecular organic materials have limited solubility and small molecular mass, resulting in their relatively small viscidity so that it’s hard to use them to fabricate thin films by spin coating process.

Ultrasonic spray coating process which has a high material utilization over 90%, has drawn the attention as a new deposition technique for low-cost photoelectric and it also shows the potential to form organic thin film from low viscidity organic solution. Nevertheless, to date, the reported photoelectric devices employing ultrasonic spray coating thin films are mostly organic photovoltaic, and there are only few reports on OLEDs due to their higher requirements for film quality.