A Novel Multiple-Ring Aromatic Spacer Based 2D Ruddlesden–Popper CsPbI_3 Solar Cell with Record Efficiency Beyond 16

摘要

Two-dimensional (2D) Ruddlesden–Popper (RP) CsPbI_3 perovskite possessessuperior phase stability by introducing steric hindrance. However, due to thequantum and dielectric confinement effect, 2D structures usually exhibit largeexciton binding energy, and the charge tunneling barrier across the organicinterlayer is difficult to eliminate, resulting in poor charge transport andperformance. Here, a multiple-ring aromatic ammonium, 1-naphthylamine(1-NA) spacer is developed for 2D RP CsPbI_3 perovskite solar cell (PSC).Theoretical simulations and experimental characterizations demonstrate thatthe 2D RP CsPbI3 perovskite using 1-NA spacer with extended π-conjugationlengths reduces the exciton binding energy and facilitates the efficientseparation of excitons. In addition, its cations have a significant contributionto the conduction band, which can reduce the bandgap, promote electroniccoupling between organic and inorganic layers, and improve interlayercharge transport. Importantly, the strong π–π conjugation of 1-NA spacercan enhance intermolecular interactions and hydrogen bonding, and preparehigh-quality films with preferred vertical orientation, resulting in lower defectdensity, and directional charge transport. As a result, the (1-NA)_2(Cs)_3Pb_4I_(13)PSC exhibits a record 16.62 performance with enhanced stability. This workprovides an efficient approach to improve charge transport and device performanceby developing multiple-ring aromatic spacers.