Functionalized wide-bandgap photoanode via dimensional design using amine fluoride salt to maximize the performance of perovskite solar cells

For Wide-bandgap (WBG) perovskite solar cells (PSCs), severe open-circuit voltage loss (Vloss) and device stability limit its photovoltaic performance. Dimensional design has been considered as a potential way to construct more efficient perovskite photoanodes. Herein, this article introduces 3-(trifluoromethyl) phenethylamine hydroiodide (CF3PEAI) to form dimensionally graded perovskite film was fabricated with 2D (two dimensional) CF3PEA2PbI4 forming on the 3D(three dimensional) perovskite layer. Studies have found that the deposited 2D perovskite can effectively regulate the energy level with minimized mismatch. Besides the functional groups in CF3PEAI can deactivate varieties of traps in perovskite through various interactions such as coordination of Iwith Pb2+, hydrogen bonding of CF3 with formamidine, and ionic interactions of NH3+ with lead halide anions, thereby reducing the charge carrier recombination at the interface, and promoting the hole transfer from perovskite to Spiro-OMeTAD. Consequently, the resulting WBG perovskite(1.75 eV) system obtained a high opencircuit voltage of 1.29 V, with power conversion efficiency (PCE) increased from 16.12% to 18.70%. In addition, the wet stability of the WBG PSCs is significantly improved due to the fluorination effect of 2D perovskite for isolating water and oxygen.