Simulation Studies on CdTe/CdS Solar Cells with Polymer Back Contact

Cadmium Telluride/Cadmium sulfide (CdTe/CdS) solar cells are one of most studied thin film solar cells, and their efficiencies have reached up to 22.1%. In order to improve the efficiency, a good ohmic back-contact on p-type CdTe is needed. However, CdTe has a high electron affinity (about 4.5 eV), making it hard for a metal to form a good ohmic contact with CdTe. Conducting polymers, with their high work function and conductivity, can be a good alternative for metal back-contact of CdTe solar cells. In our previous studies, we have showed that PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) can be used as the back-contact of CdTe solar cells, and the results are very promising.

To further understand how different parameters of PEDOT:PSS affect the CdTe solar cell, we did simulation studies on those CdTe solar cells with PEDOT:PSS back-contact using wxAMPS simulation software. We compared our simulation results with our experimental result, and explored further what parameters are needed for PEDOT:PSS to be a good back-contact of CdTe solar cells.