π–π Stacking at the Perovskite/C₆₀ Interface Enables High‐Efficiency Wide‐Bandgap Perovskite Solar Cells

Abstract

Interface passivation is a key method for improving the efficiency of perovskite solar cells, and 2D/3D perovskite heterojunction is the mainstream passivation strategy. However, the passivation layer also produces a new interface between 2D perovskite and fullerene (C60), and the properties of this interface have received little attention before. Here, the underlying properties of the 2D perovskite/C60 interface by taking the 2D TEA2PbX4 (TEA = C6H10NS; X = I, Br, Cl) passivator as an example are systematically expounded. It is found that the 2D perovskite preferentially exhibits (002) orientation with the outermost surface featuring an oriented arrangement of TEACl, where the thiophene groups face outward. The outward thiophene groups further form a strong π–π stacking system with C60 molecule, strengthening the interaction force with C60 and facilitating the creation of a superior interface. Based on the vacuum‐assisted blade coating, wide‐bandgap (WBG, 1.77 eV) perovskite solar cells achieved impressive records of 19.28% (0.09 cm2) and 18.08% (1.0 cm2) inefficiency, respectively. This research not only provides a new understanding of interface processing for future perovskite solar cells but also lays a solid foundation for realizing efficient large‐area devices.

Interface Regulation via an Organometallic Ferrocene-Based Molecule toward Inverted Perovskite Solar Cells

“…36−38 More importantly, the thiophene group can form a strong π−π stacking system with C60 and PCBM molecules in inverted PSCs, thereby effectively improving the transfer of interface charges. 39,40 Therefore, designing more efficient novel materials based on ferrocene derivatives with thiophene groups that can simultaneously passivate defects in perovskites and enhance charge transport capabilities to significantly optimize interfaces can further propel the development of PSCs.…”

“…It is noteworthy that the π−π stacking interactions established between the interface layer modification materials and the electron transport layer materials play a pivotal role in enhancing the transfer of interface charges. 39,40 To highlight the chemical structural advantages of the newly designed FcTTPc molecule, ESP analysis and DFT calculations were utilized to analyze and compare the interactions between our designed molecule FcTTPc and previously reported ferrocene molecules (Ferrocene (Fc) 28,29 and ferrocenyl-bis-thiophene-2-carboxylate (FcTc 2 ) 31 ) used in perovskites, with both perovskite and PCBM. From the ESP results (Figure S4), the newly designed FcTTPc molecule exhibits a significantly increased dipole moment (6.12 debye) compared to Fc (0.003 debye) and Fc (2.10 debye).…”