The Electric Mechanism of Surface Pretreatments for Dye-Sensitized Solar Cells Based on Internal Equivalent Resistance Analysis

Based on the optimization of dye-sensitized solar cell (DSC) photoelectrodes pretreated with different methods such as electrodeposition, spin-coating and TiCl₄ pretreatment, theoretical calculations are carried out to interpret the internal electric mechanism. The numerical values, including the series resistance R_s and the shunt resistance R_sh corresponding to the equivalent circuit model, are well evaluated and confirm that the DSC has good performance with a high R_sh and a low R_s due to good electrical contact and a low charge recombination after the different modifications. The I–V curves are fitted in the case without series resistance, and account for the role of R_s in the output characteristics. It is found that when R_s tends to the infinitesimal, the short−circuit current I_sc, the open−circuit voltage V_oc and the fill factor can be improved by almost 0.8–1.4, 2.9 and 2.1–6.8%, respectively.