Highly Efficient and Stable Solar Cells with 2D MA3Bi2I9/3D MAPbI3 Heterostructured Perovskites

Organic–inorganic hybrid lead halide perovskites are emerging as highly promising candidates for highly efficient thin film photovoltaics due to their excellent optoelectronic properties and low‐temperature process capability. However, the long‐term stability in ambient air still is a key issue limiting their further practical applications. Herein, the enhancement of both performance and stability of perovskite solar cells is reported by employing 2D and 3D heterostructured perovskite films with unique nanoplate/nanocrystalline morphology. The 2D/3D heterostructured perovskites combine advantages of the high‐performance lead‐based perovskite 3D CH3NH3PbI3 (MAPbI3) and the air‐stable bismuth‐based quasi‐perovskite 2D MA3Bi2I9. In the 2D/3D heterostructure, the hydrophobic MA3Bi2I9 platelets vertically situate between the MAPbI3 grains, forming a lattice‐like structure to tightly enclose the 3D MAPbI3 perovskite grains. The solar cell based on the optimal 2D/3D (9.2%) heterostructured film achieves a high efficiency of 18.97%, with remarkably reduced hysteresis and significantly improved stability. The work demonstrates that construction of 2D/3D heterostructured films by hybridizing different species of perovskite materials is a feasible way to simultaneously enhance both efficiency and stability of perovskite solar cells. Hydrophobic 2D MA3Bi2I9 platelets vertically situate between 3D CH3NH3PbI3 (MAPbI3) grains to form unique lattice‐like structured 2D/3D heterostructured perovskite films. The 2D/3D heterostructured perovskites combine advantages of the high‐performance lead‐based MAPbI3 and the air‐stable bismuth‐based MA3Bi2I9. The solar cell based on the optimal 2D/3D (9.2%) heterostructured film enhances both efficiency and stability of perovskite solar cells.