Extracting impedance spectroscopy curve of solar cells from scattered measurements under light illumination

Abstract Data scattering occurs in impedance spectroscopy (I-S) measurement of solar cells under light illumination, which impedes reliable data fitting for photovoltaic parameter extraction. This paper reports a method that enables reliable I-S data fitting from severely scattered I-S plots. The study shows that a valid curve fitting of I-S data is possible by using a part of the data hidden in a seemingly scattered plot. Theoretical analysis confirms the validity of this approach, which reveals that a pattern emerging from the data obtained over a high frequency range represents the genuine part of the I-S curve. This new method was employed to investigate several commercial silicon solar cells. The results show that the photovoltaic parameters of solar cells under 1 sun illumination can be extracted with good repeatability from severely scattered measurement data, offering the capability of determining the dynamic properties of the solar cells, such as junction capacitance and charge carrier lifetime under a condition that is not possible previously.