Application to Different Thin Film Solar Cell Technologies of Explicit Analytic Solutions for their Parameters Extraction from Current Versus Voltage Characteristics at Different Temperature

Abstract

In this work, we have compared three different methods for thin film solar cell electronic transport parameters extraction from dark current versus voltage at different temperatures (I (V,T) ) measurements. These parameters correspond to the classical dc single diode model with series and shunt resistances. We have implemented with Matlab two different methods recently proposed in the literature. The first method, which is exact, is based on the use of the Lambert function to solve analytically the non-explicit equation describing the electrical equivalent circuit. The second method, which is an approximate one, consists in separating the I-V characteristics into two parts, a linear and an exponential one to derive the parameters which are the most significant for each zone. A third method has also been used with a variational least squares minimisation over all data points. These methods have been applied to two different thin film solar cell technologies, amorphous silicon base p-i-n cell and CIGSe/CdS (or ZnS) hetero-junctions. We have analyzed the temperature evolution of the 4 extracted parameters of amorphous silicon base p-i-n cell and CIGSe/CdS (or ZnS) hetero-junctions solar cells under dark conditions (series and parallel resistance, saturation current density and ideality factor of the diode). This gives us insight on the electronic transport in the solar cell. We discuss the validity range of a single diode model and we establish the complementarity of these methods over a range of temperatures.