Abstract
Surface passivation and interface modification are effective strategies to acquire outstanding performances for perovskite solar cells (PeSCs). To suppress charge recombination and enhance the stability of the perovskite device, a hydrophobic two-dimensional (2D) perovskite is presented to construct a 3D-2D composite perovskite, passivating the perovskite surface/interfacial imperfection. Herein, a 3D-2D heterojunction perovskite is in situ synthesized on a 3D surface to maximize the charge transport and environmental stability. Through optimizing the annealing procedure systematically, the champion 3D-2D carbon-based PeSC achieves a power conversion efficiency of 17.95% and has wonderful long-term stability. Especially, an improved 3D-2D (3D-2D+) PeSC from restrict annealing even maintains 96.2% of the initial efficiency in air over 800 h and 90% efficiency under continuous 70 °C heating for 10 h owing to the passivation of the surface and thorough crystal boundary for the 3D-2D+ perovskite. The strong environmental stability of 3D-2D PeSCs has provided a wider avenue for fully low-temperature carbon-based PeSCs.