Improved 3D–2D Perovskite for Efficient Perovskite Photovoltaics with Low-Temperature Carbon Electrodes

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.