Silicon micro venturi nozzles for cost-efficient spray coating of thin organic P3HT/PCBM layers

Improvements on spray coating are of particular interest to different fields of technology as it is a scalable deposition method and processing from solutions offer various application possibilities outside of typical facilities. When it comes to the deposition of expensive and film-forming media such as organic semiconductors, consumption and nozzle cleaning issues are of particular importance. We demonstrate the simple steps to design and fabricate micro venturi nozzles for economical spray coating with a consumption as low as 30-50 µl centerdot min$^{-1}$. For spray coating an active area of 25 cm$^{2}$ a 2.45-4.01 fold coating efficiency is observed compared to a conventional airbrush nozzle set. The electrical characterization of first diodes sprayed with an active layer thickness of ~750 nm using a single micronozzle at a coating speed of 1.7 cm2 centerdot min−1 reveals a good external quantum efficiency of 72.9% at 532 nm and a dark current of ~7.4 centerdot 10$^{-5}$ mA centerdot cm$^{-2}$, both measured at  −2 V. Furthermore, the high resistance of the micronozzles against solvents and most acids is provided through realization in a silicon wafer with silicon dioxide encapsulation, therefore allowing easy and effective cleaning.