Perovskite/CIGS Tandem Solar Cells: From Certified 24.2% toward 30% and Beyond
Marko Jošt, Eike Köhnen, Amran Al‐Ashouri, Tobias Bertram, Špela Tomšič, Artiom Magomedov, Ernestas Kasparavičius, Tim Kodalle, Benjamin Lipovšek, Vytautas Getautis, Rutger Schlatmann, Christian A. Kaufmann, Steve Albrecht, Marko Topič
Abstract
We demonstrate a monolithic perovskite/CIGS tandem solar cell with a certified power conversion efficiency (PCE) of 24.2%. The tandem solar cell still exhibits photocurrent mismatch between the subcells; thus optical simulations are used to determine the optimal device stack. Results reveal a high optical potential with the optimized device reaching a short-circuit current density of 19.9 mA cm-2 and 32% PCE based on semiempirical material properties. To evaluate its energy yield, we first determine the CIGS temperature coefficient, which is at -0.38% K-1 notably higher than the one from the perovskite subcell (-0.22% K-1), favoring perovskite in the field operation at elevated cell temperatures. Both single-junction cells, however, are significantly outperformed by the combined tandem device. The enhancement in energy output is more than 50% in the case of CIGS single-junction device. The results demonstrate the high potential of perovskite/CIGS tandem solar cells, for which we describe optical guidelines toward 30% PCE.