Optoelectronic modeling and sensitivity analysis of a four-terminal all-perovskite tandem solar cell – Identifying pathways to improve efficiency

Abstract

We develop an optoelectronic model for a four-terminal all-perovskite tandem solar cell comprising a top and a bottom cell that are mechanically stacked together. In essence, the model captures conservation of charge carriers, the electric field via the Poisson equation, the coherent and incoherent light propagation and subsequent carrier generation and recombination mechanisms. Experiments for the stand-alone bottom and top cells as well as the tandem cell calibrate and validate the model with overall good agreement. To elucidate the relative importance of the geometrical and material parameters, a stochastic Monte Carlo simulation is carried out with a sample size of ten thousand for thirty-six simultaneously varied parameters. These parameters are ranked according to their influence on the efficiencies of the top, bottom, and tandem cell: The thicknesses for the top- and bottom-cell transparent electrode layers are ranked amongst the highest. Finally, we show how one can fine-tune the layer thicknesses to enhance the tandem efficiency from the base case of 23.1% to 24.4% and carry out further optimizations.