High-energy optical transitions and optical constants of CH$_3$NH$_3$PbI$_3$ measured by spectroscopic ellipsometry and spectrophotometry

• DOI: 10.48550/arxiv.1909.03907
• Publication Date: 2019-01-01
• Authors: Christopher G. Ba...; Giacomo Piana; Pavlos G. Lagoudakis
• Keywords: Ellipsometry; Spectrophotometry

Optoelectronics based on metal halide perovskites (MHPs) have shown substantial promise, following more than a decade of research. For prime routes commercialization such as tandem solar cells, optical modeling is essential for engineering device architectures, which requires accurate data the materials utilized. Additionally, comprehensive understanding fundamental material properties vital simulating operation devices design purposes. In this article, we use variable angle spectroscopic ellipsometry (SE) to determine constants CH$_3$NH$_3$PbI$_3$ (MAPbI$_3$) thin films over photon energy range 0.73 6.45 eV. We successfully model ellipsometric using six Tauc-Lorentz oscillators three different incident angles. Following this, critical-point analysis complex dielectric constant identify well-known transitions at 1.58, 2.49, 3.36 eV, but also additional 4.63 and 5.88 are observed in both SE spectrophotometry measurements. This work provides important information relating band structure MAPbI$_3$, can assist development potential applications material.