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Experimental Determination of Complex Optical Constants of Air‐Stable Inorganic CsPbI 3 Perovskite Thin Films
Author(s) -
Yan Wensheng,
Guo Yi,
Beri Deski,
Dottermusch Stephan,
Chen Haining,
Richards Bryce S.
Publication year - 2020
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202000070
Subject(s) - perovskite (structure) , thin film , materials science , tandem , band gap , ellipsometry , solar cell , spin coating , optoelectronics , photovoltaic system , optics , nanotechnology , crystallography , chemistry , composite material , ecology , biology , physics
Air‐stable inorganic cesium lead iodide (CsPbI 3 ) perovskite thin films with a bandgap of 1.7 eV are a promising candidate for tandem cell solar cells, comprising a perovskite top cell with a crystalline silicon bottom cell. The device design and simulations are important to develop high‐efficiency photovoltaic devices. However, knowledge of complex optical constants of the CsPbI 3 thin films is mandatory to complement such tasks. Herein, air‐stable inorganic CsPbI 3 perovskite thin films are prepared using one‐step synthesis through a spin‐coating method. Variable angle spectroscopic ellipsometry (VASE) is then conducted at five angles (43.9°, 48.9°, 53.9°, 58.9°, and 63.9°) to obtain ellipsometric data (Ψ and Δ). The thickness nonuniformity model of the perovskite thin film combined with an effective medium approximation for describing rough surface is adopted to achieve excellent fitting. The complex optical constants of the CsPbI 3 thin film are experimentally obtained in the wavelength range of 300–1200 nm. The present results open the door for design and simulations on high‐efficiency CsPbI 3 /c‐Si tandem solar cells.