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.