Coating Performance Prediction using a Modified Spin Coater and the Taguchi Technique for Solar Cells
Authors: Purushothaman Srinivasan , Heeravathi S. , Arulvendhan K. , Gohul M. , Saravanan G. 
Published: January 2024

Background:
This paper presents a novel approach to enhance the efficiency of solar
cells by employing a modified spin coating technique with a Zinc oxide (ZnO) solution. Spin coating,
known for its ability to achieve uniform, thin coatings on flat to moderately curved surfaces,
serves as the central method in this research. The study meticulously investigates various factors
affecting the coating process, including the volume of the solution, spinning speed, and spinning duration.
To optimize these factors effectively, the Taguchi approach is employed, aiming to achieve
the desired ZnO layer thickness and uniformity. The experimental findings reveal that the most favorable
results are obtained when implementing a 3-second spin cycle at a rapid spin speed of 2000
rpm while using a ZnO solution volume of 5 microliters. Furthermore, advanced techniques such as
scanning electron microscopy (SEM) are harnessed to scrutinize the surface characteristics of the
ZnO layer and its interaction with the solution. To gauge the quality of the coatings, the signal-tonoise
ratio (SNR) main impact plot is thoughtfully utilized. Subsequent in-depth analysis, employing
the analysis of variance (ANOVA) technique, delves into the intricate relationship between the experimental
parameters and the response parameter. The research outcomes are nothing short of remarkable,
showcasing that the modified spin coating technique significantly elevates the efficiency
of coated solar cells, ultimately achieving an impressive efficiency rate of 5.4%. In summation, this
study introduces a pioneering spin coating technique tailored for solar cell applications with ZnO
solution, leading to substantial enhancements in efficiency. The thorough optimization of process
parameters through the Taguchi technique, coupled with the comprehensive analysis of experimental
results via ANOVA, not only advances the comprehension of the coating process but also paves the
way for more efficient and sustainable solar cell applications in the future.

Methods:
The research systematically explored critical factors affecting the coating process for
solar cells, optimizing the ZnO layer's thickness and uniformity. The ideal parameters identified
were a 3-second spin cycle at 2000 rpm with a ZnO solution volume of 5 microliters. Quality assessment
was done using the signal-to-noise ratio (SNR) main impact plot, and further analysis via
ANOVA revealed intricate parameter relationships. These findings offer a precise and efficient method
for improving solar cell coatings, promising enhanced efficiency in renewable energy production.

Results:
The research achieved a minimum film thickness of 4.2 micrometers and revealed a correlation
between spinning speed and film thickness. Solar cell efficiency reached an impressive
5.4% post-ZnO coating. The modified spin coating device outperformed conventional methods,
enhancing efficiency by 5% to 10%. These results signify a significant breakthrough in improving
solar cell performance and hold promise for more efficient solar energy production.

Conclusion:
This research optimized the spin coating process to apply ZnO solution to solar cells,
achieving the desired film thickness. Ideal parameters were found: 2000 rpm spinning speed, three
seconds spinning duration, and four microliters of solution. This resulted in a minimum film
thickness of 4.2 micrometers. Higher spinning speeds correlated with thinner films, as shown in a
contour plot. Solar cell efficiency reached 5.4% after the ZnO coating. A redesigned spin coating
device outperformed conventional methods, improving efficiency by 5% to 10%. This modified
technique holds promise for more efficient solar panel production.