Mechanism of bifunctional p-amino benzenesulfonic acid modified interface in perovskite solar cells

5‐Chloroindole as Interface Modifier to Improve the Efficiency and Stability of Planar Perovskite Solar Cells

“…The work functions (E F ) of SnO 2 , SnO 2 /indole, and SnO 2 /Cl-indole films are calculated using formulas to be 2.28, 2.78, and 3.57 eV, respectively, and the valence band (E V ) levels are À7.96, À8.21, and À8.39 eV, respectively. [24,30,31,49] Linked with the optical bandgap value, the conduction bands (E C ) of SnO 2 , SnO 2 /indole, and SnO 2 /Cl-indole are measured to be À4.07, À4.33, and À4.51 eV, respectively. Figure 4d displays the corresponding energy levels of PSC functional layers.…”

“…[52] In addition, the ÀNH contained in the modified layer can generate a hydrogen bond with I (NÀH…I), which can effectively inhibit the diffusion of cations and improve the crystal quality of the perovskite materials. [24,35] The synergistic passivation effect of the interface modification layer can reduce the defect density, make the energy band match at the interface, facilitate better carrier transport and extraction, and achieve higher J SC and FF. [35] As shown in the concentration efficiency distribution diagram in Figure S9, Supporting Information, indole and Cl-indole are used as the modifier molecules of the SnO 2 ETL/perovskite LAL interface.…”

“…In addition, the Cl 2 p binding energy of Cl‐indole deposited on the surface of PbI 2 was transferred to 198.03 eV, which may be ascribed to the interaction of electron‐rich Cl with uncoordinated Pb 2+ . [ 24 ] Subsequently, the oxidation state of the O 1 s peak in SnO 2 , SnO 2 /indole, and SnO 2 /Cl‐indole films was measured using XPS (Figure S5, Supporting Information). The O 1 s peak indicates that 531.6 eV comes from the oxygen vacancies in the SnO 2 ETL and 530.5 eV comes from the O−Sn−O combination in the SnO 2 ETL.…”

“…The reason is probably that −NH or −Cl can provide electrons for the uncoordinated Pb to passivate Pb−I antisite defects. [ 24 ] When the surface defects are reduced, the nonradiative recombination of the device can be greatly reduced, and the FF of the device can be significantly improved. [ 25 ] Then, to prove that N–H contained in the five‐membered ring in indole and Cl‐indole may generate an N–H…I hydrogen bond interaction with the iodine of the perovskite film, we measured the Fourier‐transform infrared spectroscopy (FTIR) of the perovskite film before and after modification.…”

“…[ 23 ] Yu and colleagues used p‐amino benzenesulfonic acid (ABSA) to passivate the uncoordinated Sn 4+ in SnO 2 and the Pb−I antisite defect in the perovskite layer, thereby increasing the efficiency to 20.38%. [ 24 ] Sonmezoglu et al introduced 2‐methylbenzimidazole (MBIm) into the interface between the SnO 2 ETL and the perovskite LAL to minimize nonradiation combination losses and obtain high stability and an efficiency of 21.6% of PSCs. [ 25 ] These articles prove the importance of interface modification between ETL and perovskite for improving the PV performance of the device.…”