Simulation of a CdSe/Sb₂Se₃ Tandem, Bifacial, Photovoltaic Device

A comprehensive simulation platform was developed for tandem, bifacial photovoltaic (PV) devices using COMSOL Multiphysics® software and demonstrated with a CdSe top cell and Sb<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Se<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> bottom cell. The model allows for monolithic schemes based on a tunnel junction, a recombination interface, or an Ohmic, idealized interconnection. The Ohmic connection is facilitated by integrating the simulated top and bottom cells in a customized electric circuit model. Rigorous optical physics based on Maxwell’s wave equation enables detailed optimization required for these multi-layer, bifacial systems. We explore the impacts of the recombination interface on device performance and determine the optimal conditions for current matching between the top and bottom cells. The simulated device has an efficiency of 29% for one-sided illumination and marginally increases to 29.25% in bifacial mode. We note that optimizing the tandem device for bifacial operation requires revisiting the absorber band gaps and thicknesses. Avenues for significant improvement are discussed.