A low-cost method of converting solar irradiation to electricity, polymeric solar cells, may be one of the most promising in the near future. The use of ultrasonic spray nozzle technology has been studied to see if it may lower the cost of manufacturing while simultaneously improving the performance of polymeric solar cells.

Polymeric solar cells generate electricity by the use of active organic layers in their construction. Polymeric-based solar cells make use of electrically conductive polymers, which are less expensive than crystalline silicon-based systems and can be used to generate electricity. These polymers can also be coated onto solar cells utilizing a variety of processes, each of which has its own impact on the possible cost of production and on the overall performance of the polymeric solar cell (Figure 1).

As part of a collaboration with the Colorado School of Mines, the National Center for Photovoltaics, and the National Renewable Energy Laboratory, the efficiency and performance of ink jet printing, airbrush spraying, ultrasonic spraying, slot coating, and screen coating were all evaluated for their effectiveness and efficiency. Ultrasonic spray technique, out of all of these technologies, produced the most promising outcomes, according to the researchers.

It was discovered that ultrasonic spray technique was not only cost-effective, but it also created a uniform coating of photoconductive substances on the surface. Ultrasonic spray technology, in its most basic form, works by ultrasonically atomizing film coatings into droplets that are highly consistent, precisely formed, and evenly spaced, and then depositing them onto a substrate under precise control. In this work, ultrasonic spray nozzles deposited droplets as small as 18 microns in diameter, making it simple to construct a coating to the appropriate thickness. The material under investigation was a liquid solution of poly (3-hexylthiophene) (P3HT) and [6,6] phenyl-C61 butyric-methyl ester (PCBM) in either chlorobenzene or p-xylene, which were utilized as carrier solvents in the experiment. These layers included poly (3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT: PSS), indium-tin oxide (ITO), and glass, which were all coated with this coating.

P3HT:PCBM thin films were sprayed with a solvent such as chlorobenzene or p-xylene, and the reactions were seen using various instruments, such as x-ray diffraction, optical microscopy, and other techniques. These solvents had nearly comparable characteristics, however they produced significantly different results. The efficacy of these reactions in terms of power generation was evaluated in order to assess the implications of these reactions. Interestingly, the chlorobenzene film had an efficiency of 3 percent, which was enhanced to 3.2 percent by layering more chlorobenzene layers on top of the active layer. P-xylene, on the other hand, had a very low efficiency in terms of power production, averaging around 0.1 percent. This result was linked to the difference between P3HT and PCBM, and it was determined that spraying additional layers of P-xylene would have no effect on it.

Following the findings of this investigation, it is concluded that ultrasonic spray technique has promise for the future low cost scalability of organic-based polymeric solar cells. It has been demonstrated that the choice of solvent, as well as the processing conditions for appropriate film build, have a significant impact on the final results. Future studies, according to the scientists, should focus on how to change surface roughness and further fine-tune solvent blends in order to obtain more efficient cell performance.