Performance optimization of monolithic all-perovskite tandem solar cells under standard and real-world solar spectra

Summary

Constructing monolithic all-perovskite tandem solar cells is a promising strategy to increase the efficiency beyond the single-junction limit. However, two fundamental questions remain unanswered: (1) is "current match" always a necessary condition of maximizing the tandem efficiency and (2) how can we minimize the current-mismatching loss under the real-world solar spectra? Herein, we answer the questions by conducting simulations using validated optical and electrical models. The best efficiency of this all-perovskite tandem structure under standard test conditions is achieved when the wide-bandgap top subcell has a higher short-circuit current density of about 1.05 mA cm⁻² than the bottom one. To answer the second question, we use real-world weather data as the inputs of the simplified models, which dramatically reduce the calculation time and improve the annual energy yield by up to 4.5%. The marginal current-mismatching losses, and even gains, ease the concern over the de-rated tandem products under real-world solar spectra.