Atomic Layer Deposition-Free Monolithic Perovskite/Perovskite/Silicon\nTriple-Junction Solar Cells

Abstract

Perovskite/perovskite/silicon\n(PVSK/PVSK/Si) triple-junction (3J)\ntandem solar cells may exhibit higher efficiencies than their PVSK/Si\ndouble-junction (2J) counterparts; however, their best efficiency\nis still significantly lower due to the chemical degradation of the\nPVSK middle cell by solvents and the poor performance of the PVSK\ntop cell. This paper reports the use of a highly volatile solvent\nmixture to prevent solvent penetration across the recombination layer\nbetween two PVSK subcells and to demonstrate efficient PVSK/PVSK tandems\neven without atomic layer deposition protection layers. The photovoltaic\nperformance of the PVSK top cell, with a bandgap energy of 1.96 eV,\ncan be improved from 6.4% to 13.9% by adding urea, mainly due to the\nenhanced crystallinity and light-absorbing capability. With the aid\nof the new volatile solvent and the urea additive, the final monolithic\nPVSK/PVSK/Si 3J tandems exhibited a record-high conversion efficiency\nof 22.23%.