Accounting for Fabrication Variability in Transparent Perovskite Solar Cells for Four-Terminal Tandem Applications

Opto-electronic models that seek to predict the performance of perovskite and tandem solar cells (PSCs/TSCs) often keep the optical and recombination parameters (ORPs) constant in subsequent studies. During fabrication of PSCs, however, these parameters can vary significantly. To account for the inherent fabrication variability, a comprehensive opto-electronic-electric model to predict the current-voltage characteristics of four-terminal (4T) TSCs is developed. This model is calibrated with forty-eight in-house fabricated transparent PSCs with perovskite layer thickness of 420, 550, and 700 nm and corresponding median efficiencies of 20.6%, 21.1%, and 21.0%, respectively; a CIS bottom cell with stand-alone efficiency of 17.5%; and combined 4T TSCs with a median efficiency of 29.0%. After fitting and validation, the functional forms of the ORPs are captured to estimate how they change with perovskite layer thickness. Finally, the errors with models assuming constant ORPs are demonstrated and how to improve the TSCs efficiency to more than 30% is discussed.