25.1% Higha??Efficient Monolithic Perovskite Silicon Tandem Solar Cell with a High Band Gap Perovskite Absorber

摘要： Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum band gap, high quantum efficiency, and high stability of the perovskite. Here, we combine a silicon heterojunction bottom cell with a perovskite top cell with an optimum band gap of 1.68 eV in planar p-i-n tandem configuration. Methylammonium-free FA0.75Cs0.25Pb(I0.8Br0.2)3 perovskite with high Cs-content is investigated for improved stability. A 10% molarity increase to 1.1 M of the perovskite precursor solution resulted in ~75 nm thicker absorber layers and 0.7 mA/cm2 higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of ~80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over five months showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved anti-reflection measures, the high band gap perovskite absorber has the potential for 30% tandem efficiency in the near future.