Two birds with one stone: Simultaneous realization of constructed 3D/2D heterojunction and p-doping of hole transport layer for highly efficient and stable perovskite solar cells

Combined with the superb moisture and thermal stability of two-dimensional (2D) perovskites and the excellent photoelectronic features of three-dimensional (3D) perovskites, building 3D/2D structure has been proved to be an auspicious way to improve both power conversion efficiency (PCE) and durability of perovskite solar cells (PSCs). In this work, cyclohexylammonium bromide (CMABr) as p-dopant is introduced into hole transport layer (HTL) to form 3D/2D heterostructure perovskite bilayer. It is confirmed that the formation of 2D perovskite interlayer comes from the reaction between the excess PbI 2 on the surface of 3D perovskite and CMABr on the bottom of HTL, which served as moisture barrier layer to enhance the device stability. The exotic CMA + and Br − ions could insert the ABX 3 perovskite lattice to compensate A-site cation and X-site vacancies, which reduced the undesirable non-radiative recombination centers. Owing to the p-type doping, the more uniform morphology, down-shifted energy levels and improved electrical properties were obtained. Consequently, the CMABr-doped PSCs based on triple-cation (Cs + , MA + and FA + ) perovskite and double-cation (MA + and FA + ) perovskite produce maximum PCEs of 21.78 % and 23.56 %, respectively, as well as remarkable long-term device stability. The results demonstrate a novel pathway to construct 3D/2D stacking structure for highly efficient PSCs with decent stability.