| Affiliation: | 1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206 P. R. China Group for Molecular Engineering of Functional Materials, Institute of Chemical Sciences and Engineering, EPFL VALAIS, Sion, 1951 Switzerland;2. Laboratory of Quantum Photodynamics, Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991 Russia;3. Laboratory of Quantum Mechanics and Molecular Structure, Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991 Russia;4. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206 P. R. China;5. Group for Molecular Engineering of Functional Materials, Institute of Chemical Sciences and Engineering, EPFL VALAIS, Sion, 1951 Switzerland |
| Abstract: | Vertically oriented 2D perovskites exhibit promising optoelectronic properties and intrinsic stability, but their photovoltaic application is still limited by the low power conversion efficiency (PCE) compared to 3D analogs. Here, a new crystallization pathway (RCP) is reported to suppress defects in vertically oriented 2D perovskite caused by its over-rapid self-assembly behavior. By controlling the specific adsorption of an ammonium halide additive on different perovskite crystal planes, the dynamic preferred growth of (111) plane is intentionally restrained, and the minority (202) planes emerge as secondary nucleation sites to stimulate the creation of large grains. As the halogen-regulated deprotonation of ammonium proceeds, the (111) crystal plane gradually recovers its growth dominance, and a vertically oriented 2D perovskite film finally forms with high homogeneity, reduced trap density of states, and desired carrier transport/collection kinetics. Solar cells using RCP-2D films show a highly reproducible and stable PCE reaching 18.5% with a high fill factor of 83.4%. These findings provide critical missing information on simultaneously achieving highly oriented and less defective 2D perovskite films for excellent device performance. |
