Optimization and Characterization of Dip-Coated PEDOT:PSS on CdTe Solar Cells*

Organic thin film solar cells have been identified as viable photovoltaic technology alternatives to conventional power production methods. In this work, we optimize the thin film deposition conditions for high-conductive grade poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on pulsed laser deposited cadmium sulfide/cadmium telluride/indium tin oxide substrates. In our previous studies, we have determined that this particular substrate and polymer combination significantly improves the photovoltaic conversion efficiency due to a reduction of the Schottky barrier resistance. In this study, we focus on applying a uniform layer of the PEDOT:PSS back contact by optimizing thin film dip-coating parameters such as pulling rate, temperature, application duration, and drying procedures. The resultant back contacts are characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, and ellipsometry techniques. Electrical conductivity tests on full cells are also performed using a Keithley SourceMeter, and structure and efficiency results are discussed.