Spontaneous Formation of a Ligand-Based 2D Capping Layer on the Surface of Quasi-2D Perovskite Films.

Two-dimensional (2D) Ruddlesden-Popper phase perovskites (RPPs) are attracting growing attention for photovoltaic applications due to their enhanced stability compared to three-dimensional (3D) perovskites. The superior tolerance of 2D RPPs films to moisture and oxygen is mainly attributed to the hydrophobic nature of the introduced long-chain spacer cations (ligands). In this work, it is revealed that a thin capping layer, consisting of self-assembled butylammonium ligands, is spontaneously formed on the top surface of a quasi-2D perovskite film prepared by conventional one-step hot casting. Based on morphological and crystallographic analyses of both the top/bottom surfaces and the interior of quasi-2D perovskite films, the formation process of the 2D capping layer and the assembly of RPPs, comprising both large and small slab thickness (large-n, small-n), is elucidated. The vertical orientation of RPPs that is required for sufficient charge transport for 2D perovskite solar cells (PSCs) is further verified. We propose that the surface capping layer is directly responsible for the long-term stability of 2D PSCs. This work provides detailed insight into the microstructure of quasi-2D RPPs films that should assist the development of strategies for unlocking the full potential of 2D perovskites for high-performance PSCs and other solid-state electronic devices.

[1]  C. McNeill,et al.  X-ray diffraction of photovoltaic perovskites: Principles and applications , 2022, Applied Physics Reviews.

[2]  Hao Wang,et al.  Quasi-2D Bilayer Surface Passivation for High Efficiency Narrow Bandgap Perovskite Solar Cells. , 2022, Angewandte Chemie.

[3]  J. Laird,et al.  Brownian Tree‐Shaped Dendrites in Quasi‐2D Perovskite Films and Their Impact on Photovoltaic Performance , 2022, Advanced Materials Interfaces.

[4]  K. Ghiggino,et al.  Millimeter‐Sized Clusters of Triple Cation Perovskite Enables Highly Efficient and Reproducible Roll‐to‐Roll Fabricated Inverted Perovskite Solar Cells , 2021, Advanced Functional Materials.

[5]  Yuan Zhang,et al.  Surface Passivation Using 2D Perovskites toward Efficient and Stable Perovskite Solar Cells , 2021, Advanced materials.

[6]  Jinsong Huang,et al.  Stabilizing perovskite-substrate interfaces for high-performance perovskite modules , 2021, Science.

[7]  M. Green,et al.  Solar cell efficiency tables (Version 58) , 2021, Progress in Photovoltaics: Research and Applications.

[8]  Wentao Sun,et al.  Mobile Media Promotes Orientation of 2D/3D Hybrid Lead Halide Perovskite for Efficient Solar Cells. , 2021, ACS nano.

[9]  Akriti,et al.  Layer-by-layer anionic diffusion in two-dimensional halide perovskite vertical heterostructures , 2021, Nature Nanotechnology.

[10]  M. Toney,et al.  Crystallization in one-step solution deposition of perovskite films: Upward or downward? , 2021, Science Advances.

[11]  J. Noh,et al.  Intact 2D/3D halide junction perovskite solar cells via solid-phase in-plane growth , 2021 .

[12]  Yue Hu,et al.  Two-dimensional Ruddlesden–Popper layered perovskite solar cells based on phase-pure thin films , 2020 .

[13]  Zhipeng Ci,et al.  Crystallization Kinetics in 2D Perovskite Solar Cells , 2020, Advanced Energy Materials.

[14]  Yongsheng Liu,et al.  Organic‐Salt‐Assisted Crystal Growth and Orientation of Quasi‐2D Ruddlesden–Popper Perovskites for Solar Cells with Efficiency over 19% , 2020, Advanced materials.

[15]  K. Ghiggino,et al.  Crystallisation control of drop-cast quasi-2D/3D perovskite layers for efficient solar cells , 2020, Communications Materials.

[16]  Wenchao Huang,et al.  Stabilizing High Efficiency Perovskite Solar Cells with 3D-2D Heterostructures , 2020 .

[17]  Chunhua Zhou,et al.  Revealing the Role of Methylammonium Chloride for Improving the Performance of 2D Perovskite Solar Cells. , 2020, ACS applied materials & interfaces.

[18]  Akriti,et al.  Two-dimensional halide perovskite lateral epitaxial heterostructures , 2020, Nature.

[19]  Yuanhui Sun,et al.  Efficient and stable Ruddlesden–Popper perovskite solar cell with tailored interlayer molecular interaction , 2020 .

[20]  S. Tiwari,et al.  A review on perovskite solar cells: Evolution of architecture, fabrication techniques, commercialization issues and status , 2020 .

[21]  Ruipeng Li,et al.  Ligand-Size Related Dimensionality Control in Metal Halide Perovskites , 2019, ACS Energy Letters.

[22]  W. Tisdale,et al.  Excitons in 2D Organic–Inorganic Halide Perovskites , 2019, Trends in Chemistry.

[23]  Tak W. Kee,et al.  Triggering the Passivation Effect of Potassium Doping in Mixed‐Cation Mixed‐Halide Perovskite by Light Illumination , 2019, Advanced Energy Materials.

[24]  Dong Hoe Kim,et al.  Enhanced Charge Transport in 2D Perovskites via Fluorination of Organic Cation. , 2019, Journal of the American Chemical Society.

[25]  H. Ade,et al.  Unveiling the operation mechanism of layered perovskite solar cells , 2019, Nature Communications.

[26]  C. McNeill,et al.  Self‐Assembled 2D Perovskite Layers for Efficient Printable Solar Cells , 2018, Advanced Energy Materials.

[27]  Andrew H. Proppe,et al.  Compositional and orientational control in metal halide perovskites of reduced dimensionality , 2018, Nature Materials.

[28]  Peng Chen,et al.  In Situ Growth of 2D Perovskite Capping Layer for Stable and Efficient Perovskite Solar Cells , 2018 .

[29]  Jinsong Huang,et al.  Suppressed Ion Migration along the In-Plane Direction in Layered Perovskites , 2018 .

[30]  M. Chabinyc,et al.  Charge-Carrier Dynamics and Crystalline Texture of Layered Ruddlesden–Popper Hybrid Lead Iodide Perovskite Thin Films , 2018 .

[31]  Laura M. Herz,et al.  Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites , 2017, Nature Energy.

[32]  M. Kanatzidis,et al.  High Members of the 2D Ruddlesden-Popper Halide Perovskites: Synthesis, Optical Properties, and Solar Cells of (CH3(CH2)3NH3)2(CH3NH3)4Pb5I16 , 2017 .

[33]  Jun Zhang,et al.  Observation of Internal Photoinduced Electron and Hole Separation in Hybrid Two-Dimentional Perovskite Films. , 2017, Journal of the American Chemical Society.

[34]  Sergei Tretiak,et al.  High-efficiency two-dimensional Ruddlesden–Popper perovskite solar cells , 2016, Nature.

[35]  D. J. Clark,et al.  Ruddlesden-Popper Hybrid Lead Iodide Perovskite 2D Homologous Semiconductors , 2016 .

[36]  Aram Amassian,et al.  Ligand-Stabilized Reduced-Dimensionality Perovskites. , 2016, Journal of the American Chemical Society.

[37]  Aslihan Babayigit,et al.  Intrinsic Thermal Instability of Methylammonium Lead Trihalide Perovskite , 2015 .

[38]  Omar K Farha,et al.  2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications. , 2015, Journal of the American Chemical Society.

[39]  Katsuhiko Ariga,et al.  25th Anniversary Article: What Can Be Done with the Langmuir‐Blodgett Method? Recent Developments and its Critical Role in Materials Science , 2013, Advanced materials.

[40]  I. Hertel,et al.  Molecular structure of surface active salt solutions: photoelectron spectroscopy and molecular dynamics simulations of aqueous Tetrabutyl-Ammonium Iodide , 2004 .

[41]  O. J. Guentert.  Study of the Anomalous Surface Reflection of X Rays , 1965 .

[42]  X. W. Sun,et al.  High-Performance Quasi-2D Perovskite Solar Cells with Power Conversion Efficiency Over 20% Fabricated in Humidity-Controlled Ambient Air , 2021, Chemical Engineering Journal.

[43]  Yani Chen,et al.  2D Ruddlesden–Popper Perovskites for Optoelectronics , 2018, Advanced materials.

[44]  M. Kanatzidis,et al.  Understanding Film Formation Morphology and Orientation in High Member 2D Ruddlesden–Popper Perovskites for High‐Efficiency Solar Cells , 2018 .