Doped the electropolymerized PEDOT for high performance and air stable Si/organic solar cells

Poly(3,4-ethylenedioxythiophene) (PEDOT) has been electropolymerized on the Si wafer through a non-aqueous galvanostatic method, which is employed to fabricate the Si/organic solar cell for the first time. Surface morphology, film thickness as well as the sheet resistance of the PEDOT-coated Si wafer are investigated by controlling the polymerization time, and the best electropolymerization time for the Si/PEDOT device performance is 8 s. However, the pristine PEDOT film shows low carrier concentration, and the low work function is not suitable for the fabrication of high performance solar cells. Interestingly, after optimizing the PEDOT-coated Si wafer with hydrochloroplatinic acid (H2PtCl6) solution, the work function of the PEDOT film is enhanced, which raises the barrier height (Phi(SBH)) as well as V-bi between the Si and PEDOT interface. Additionally, the sheet resistance of the PEDOT layer is reduced. Both of them are beneficial for the better charge transfer and collection. As a result, the efficiency of 7.36% has been achieved by the Si/PEDOT devices, which is much higher than that of the control ones, similar to 5.49%. More importantly, due to the stable PEDOT, the Si/PEDOT solar cell shows excellent stability. These results point out a new route to develop low-cost, high performance and high stability Si/organic hybrid solar cells.