Research On Conducting Polymer Counter Electrode For Dye-sensitized Solar Cells

The Dye-sensitized Solar Cell(DSSC) is mainly composed of TiO2 anode, electrolyte and a counter electrode. The counter electrode is the critical part to determine the performance and cost, Platinum is first applied to the counter electrode due to its high conductivity and catalytic activity, but high cost limits the application. Conducting polythiophene and polypyrrole were successfully prepared by electrochemical method, and as counter electrodes used for photoelectric performance test. The properties of conducting polymers were characterized by SEM, infrared spectrum instrument, four-probe meter, XPS, and the influence of preparation conditions on the catalytic performance and photoelectrical conversion efficiency were analyzed.Polythiophene were deposited on FTO glass by constant potential method and CV method. The optimal preparation technology of constant potential method was under the condition of 1.5 V, 120 s. The optimal preparation technology of Cyclic voltammograms(CV) method was under the condition of 0-2.0 V, 5 cycles. The largest photoelectric conversion efficiency(PCE) of poly(3-brominethiophene) was prepared under condition of 1.7 V, 120 s. The largest PCE of poly(3-methylthiophene) was prepared under condition of 1.5 V, 150 s.The influences of electrodeposition conditions on PPy(TSO-) electrode’s square resistance and PCE were studied through orthogonal experiment. The electrodeposition conditions of the least square resistance and maximum PCE were determined, and the order of condition influences were analyzed. The analysis showed that the pH value of electrolyte has the most significant influence on PPy(TSO-) electrode photoelectric performance. When the pH value was 2, PPy(TSO-) square resistance was minimum and PCE was the maximum, 5.60 Ω and 2.46%, respectively. SEM images showed the cellular particles is more than others which could provide more catalytic reaction activation center, and CV test manifested that PPy(TSO-) had the highest catalytic performance.The impact of doping anions on the polypyrrole electrode properties had been studied. Through the analysis of XPS, PPy(DBS-) element doped rate was the highest, reached 0.86. CV curves also indicated that PPy(DBS-) had high catalytic performance and stability. Eletrochemical Impedance Spectroscopy(EIS) manifested that PPy(DBS-) Rct and C were10.99 Ω·cm2 and 3.22 μF, respectively. PPy(DBS-) square resistance was minimum and PCE was the maximum, 5.66 Ω and 2.49%, respectively. The PCE was 77.57% of Pt electrode.