Modulating Buried Interface to Achieve an Ultra‐High Open Circuit Voltage in Triple Cation Perovskite Solar Cells

Abstract This work proposes a methodology to increase the open‐circuit voltage of perovskite solar cells via modulating the buried interface using π‐conjugated molecules, featuring a push‐pull electronic structure configuration. In the planar perovskite solar cells using tin oxide nanocrystal as an electron transport layer, the 2‐methyl‐1‐aminobenzene derivatives with 4‐(Heptafluoropropan)‐2‐methylaniline notable not only reduce the interfacial energy barrier but also passivate the defects at the buried interface. This modulation enhances the open circuit voltage of Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 (bandgap ≈1.60 eV) perovskite solar cell to a high value of 1.241 V and thus the power conversion efficiency to 24.16% under standard testing condition. An even higher efficiency of 25.11% can be achieved when employing in the Cs 0.05 MA 0.05 FA 0.9 PbI 3 (bandgap ≈1.54 eV) perovskite solar cell. The open circuit voltage (1.241 V) is among the highest in triple‐cation perovskite solar cells which reaches 95% Shockley–Queisser limit. A solar‐to‐CO conversion efficiency of 11.76% can be achieved in the fabricated perovskite solar minimodule driven carbon dioxide electrolyzer. This demonstrates the potential of utilizing perovskite solar cells for CO 2 conversion as a clean and green energy environment.