Synergistic Defect Passivation and Crystallization Modulation in Efficient Perovskite Solar Cells: The Case of Multifunctional 2-Anisidine-4-Sulfonic Acid

Abstract

With the continuous development of the performance of perovskite solar cells, the high-density defects on the perovskite film surface and grain boundaries as well as undesired perovskite crystallization are increasingly emerging as challenges to their commercial application. Herein, a dye intermediate 2-anisidine-4sulfonic acid (2A4SA), containing sulfonic acid group (SO 3 − ), amino group (−NH 2 ), methoxy group (CH 3 O−), and benzene ring, which exhibit a synergistic effect in comprehensive defect passivation and crystallization modulation, is incorporated. Detailed investigations show that the SO 3 − of 2A4SA with high electronegativity firmly chelates with uncoordinated lead ions through the coordination interaction, while the −NH 2 and the CH 3 O− of 2A4SA separately immobilize iodide ions and organic cations in the perovskite lattice through hydrogen bonds, enabling substantially decreased nonradiative recombination and trap state density. Meanwhile, 2A4SA molecules attached to the surface of perovskite nuclei can delay crystallization kinetics and promote preferred vertical growth orientation, thereby attaining the high-crystallinity and large-size-grain perovskite films. Consequently, the 2A4SA-doped device with the structure ITO/SnO 2 /Cs 0.15 FA 0.75 MA 0.10 PbI 3 (2A4SA)/Spiro-OMeTAD/Ag presents a splendid power conversion efficiency (PCE) of 23.06% accompanied by increased open-circuit voltage (1.15 V) and fill factor (82.17%). Furthermore, the optimized film and device demonstrate enhanced long-term stability. The unencapsulated optimized device retains ≈80% of the original PCE after 1000 h upon exposure to ambient atmosphere (20−50% RH), whereas the control group is only 56.8%.

Enhancing the Efficiency and Stability of Inverted Formamidinium-Cesium Lead-Triiodide Perovskite Solar Cells through Lewis Base Pretreatment of Buried Interfaces

“…The interaction between the BA molecule and perovskite was detected by Fourier transform infrared (FTIR) spectroscopy. 33 As shown in Figure 3d, characteristic stretching vibrations of C�O arose in pure BA film at about 1656.07 cm −1 . 34 Perovskite and PbI 2 specimen also appeared C�O bond stretching at 1649.80 cm −1 after BA was modified.…”

“…The interaction between the BA molecule and perovskite was detected by Fourier transform infrared (FTIR) spectroscopy . As shown in Figure d, characteristic stretching vibrations of CO arose in pure BA film at about 1656.07 cm –1 .…”