Open AccessOptical modeling of wide-bandgap perovskite and perovskite/silicon tandem solar cells using complex refractive indices for arbitrary-bandgap perovskite absorbers
Author(s) -
Salman Manzoor,
Jakob Häusele,
Kevin A. Bush,
Axel F. Palmstrom,
Joseph A. Carpenter,
Zhengshan J. Yu,
Stacey F. Bent,
Michael D. McGehee,
Zachary C. Holman
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.027441
Subject(s) - perovskite (structure) , band gap , materials science , refractive index , optoelectronics , formamidinium , perovskite solar cell , tandem , optics , silicon , solar cell , chemistry , crystallography , physics , composite material
Wide-bandgap perovskites are attractive top-cell materials for tandem photovoltaic applications. Comprehensive optical modeling is essential to minimize the optical losses of state-of-the-art perovskite/perovskite, perovskite/CIGS, and perovskite/silicon tandems. Such models require accurate optical constants of wide-bandgap perovskites. Here, we report optical constants determined with ellipsometry and spectrophotometry for two new wide-bandgap, cesium-formamidinium-based perovskites. We validate the optical constants by comparing simulated quantum efficiency and reflectance spectra with measured cell results for semi-transparent single-junction perovskite cells and find less than 0.3 mA/cm 2 error in the short-circuit current densities. Such simulations further reveal that reflection and parasitic absorption in the front ITO layer and electron contact are responsible for the biggest optical losses. We also show that the complex refractive index of methylammonium lead triiodide, the most common perovskite absorber for solar cells, can be used to generate approximate optical constants for an arbitrary wide-bandgap perovskite by translating the data along the wavelength axis. Finally, these optical constants are used to map the short-circuit current density of a textured two-terminal perovskite/silicon tandem solar cell as a function of the perovskite thickness and bandgap, providing a guide to nearly 20 mA/cm 2 matched current density with any perovskite bandgap between 1.56 and 1.68 eV.