Fundamental parameters extraction from dark I–V characteristics: A comprehensive study on amorphous/crystalline silicon hetero-junction solar cell

Dark current-voltage (I-V) curves are usually used to analyze the electric characteristics of solar cell device based on one-diode and two-diode equivalent circuit models. In this study, we extracted the parameters from dark I-V with Nelder-Mead algorithm and repeated error estimation method based on two-diode circuit model. If we give one set of initial values of the parameters into the Nelder-Mead algorithm, such evaluation method will show us one set of reasonable fitting results. Therefore, we will get the best fitting results after a series of set initial values evaluation based on our repeated algorithm process. The final fitting results showed that trends of F.F. were fully influenced by series resistances. With thicker p-layer, they demonstrated larger ideality factors and less short-circuit current densities. Short-circuit current densities show the opposite trend with respect to ideality factors in p-layer solar cell. However, the insertion of intrinsic thin-layer between p-layer and n-type c-Si can reduce the ideality factor. We found the calculated V_OC extracted from the dark I-V was consistent to the measured V_OC from standard solar simulator. The insertion of i-layer greatly reduced the J₀₁ and hence enhanced the V_OC.