Investigation of Two-Dimensional Layered Perovskites on Optoelectronic Properties, Composition and Their Application in Solar Cells

M-C Tang, S. Zhang, C.A. Hacker
National Institute of Standards and Technology (NIST),
United States

Keywords: 2D Perovskites, Solar Cells, X-ray photoemission spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS)

Summary:

Organic-inorganic two-dimensional (2D) layered hybrid perovskites have attracted immense attention because of their remarkable optoelectronic properties, including high absorption coefficient, long exciton diffusion length, and tunable direct bandgap.[1] Beyond traditional low bandgap 3D hybrid perovskite solar cells, namely methylammonium lead triiodide (MAPbI3), 2D layered hybrid perovskites have demonstrated a wide and tunable bandgap, suitable not only for semitransparent and transparent solar cells applications but also for blue and ultraviolet light-emitting diode and photodetector applications. In this contribution, we systematically investigate electronic structure, composition, and optoelectronic properties of 3 different materials systems including 3D, 2D layered and 2D/3D heterojunction structure perovskites (as shown in Figure 1). Our previous work on 3D systems showed a clear link between morphology, composition, electronic structure, and device properties.[2] We extend our knowledge of 3D processing to investigate confined 2D systems and the 2D/3D hybrid systems. We employ a multi-probe investigation method consisting of X-ray photoemission spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) complemented with morphology and X-ray powder diffraction (XRD) characterization of 2D layered and 2D/3D hierarchical structure perovskites to understand the trend of solar cell performance. Obtained results reveal the composition distribution, polycrystalline structure and morphology of 2D layered and 2D/3D hierarchical structure perovskite thin films. We use this insight to develop a composition engineering protocol suitable for depositing fully covered and pin-hole-free high-quality 2D layered and 2D/3D hierarchical structure perovskite thin films and present efficient single-junction photovoltaics with high stability for future industrial scaleā€up fabrication.