Statistical methods in the analysis of dye solar cell experiments

Armi Tiihonen^a, Kati Miettunen^a, Janne Halme^a, Peter Lund^a, Reko Leino^b, Denys Mavrynsky^b, Sabine Rendon^b

^aDepartment of Applied Physics, Aalto University, P.O.Box 15100, Espoo, FI-00076 AALTO, Finland

^bÅbo Akademi University, Finland, Porthaninkatu, 3, Turku, Finland

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Roma, Italy, 2015 May 11th - 13th

Organizer: Filippo De Angelis

Oral, Armi Tiihonen, presentation 052
Publication date: 5th February 2015

How do you know that your new magic material really improves the performance of your solar cells, when there is so much variance in the results from sample to sample? How do you decide that one solar cell in your experiment is an outlier that should be dropped off from the analysis? Is all hope lost, when you complete a 1000 h long light soaking aging test only to find out that your samples were exposed to somewhat different light intensities depending on their position under the lamps, causing so large scattering in the data that it seems impossible to draw any meaningful conclusions? These and many other questions can be answered using statistical methods that, nevertheless, are hardly ever used in the scientific papers published in our field, for which there can be many reasons. The biggest reason could be that statistical methods are perceived as hard to understand, difficult to use, and ineffective or even questionable when the measured series consist of only a few solar cells. It does not have to be that way. In this contribution, we use real experimental cases to present how simple statistical methods can be applied to typical experiment data gathered in the dye solar cell research, and show how they not only facilitate drawing more robust, objective conclusions from the results, but also help the researcher in her practical work. Although most statistical methods work better the larger the sample size, they are applicable and useful also for series with less than ten cells in each group. The presented methods are Peirce’s criterion, t-test, analysis of variance, and analysis of covariance [1,2]. Peirce’s criterion is a method for detecting outliers from a data set. T-test and analysis of variance are useful for drawing statistically significant conclusions from the comparison of two or more groups of cells. The analysis of covariance allows separating the effect of nuisance factors such as varying light intensity from the aging behavior of each cell group, making it possible to determine more reliably whether or not the groups aged differently. Statistical methods offer an objective way to assess and report the reliability of the results. They belong to the basic toolbox of every experimentalist. When we know which methods to use and when, and practice a little, they can become a routine that serves us and our readers well.

[1] Montgomery, D. Design and analysis of experiments. John Wiley & Sons 2008. [2] Ross, S. Peirce's criterion for the elimination of suspect experimental data. Journal of Engineering Technology 2003, 2, 38 - 41.

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.