Effect of Dilution on PEDOT:PSS Work Function

Among thin film solar cells, the CdTe solar cell (Cadmium Telluride) is favored because of its low cost and relatively high efficiency. However, its efficiency is still lower than the theoretical limit. One of the factors limiting its efficiency is the barrier created at the back contact, which affects carrier collections and thus the efficiency of the solar cell. In our previous studies, we have shown that conducting polymer poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) can be used as the back contact of CdTe solar cells, and that the efficiency of the solar cell depends on the conductivity of the polymer. These results are very promising because it indicates that conducting polymers have the potential to replace metal as the back contact of CdTe solar cell. In this work, we show our studies of the effect of dilution on the work function of PEDOT:PSS, which could affect the efficiency of CdTe solar cells. The work function of the PEDOT films prepared from different dilution levels will be measured using the KP Technologies Kelvin Probe instrument. Different preparation parameters will be adjusted to achieve a range of work functions. The results will help us gain a better understanding of how to modify the work function of PEDOT:PSS, and provide criteria for a good polymer back contact for CdTe solar cells.